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Sample records for access networks topics

  1. Optical Access Networks

    NASA Astrophysics Data System (ADS)

    Zheng, Jun; Ansari, Nirwan

    2005-01-01

    economic viability of many potential high-bandwidth applications. In recent years, optical access networks have been receiving tremendous attention from both academia and industry. A large number of research activities have been carried out or are now underway this hot area. The purpose of this feature issue is to expose the networking community to the latest research breakthroughs and progresses in the area of optical access networks.

    Scope of Contributions

    This feature issue aims to present a collection of papers that focus on the state-of-the-art research in various networking aspects of optical access networks. Original papers are solicited from all researchers involved in area of optical access networks. Topics of interest include but not limited to:
    • Optical access network architectures and protocols
    • Passive optical networks (BPON, EPON, GPON, etc.)
    • Active optical networks
    • Multiple access control
    • Multiservices and QoS provisioning
    • Network survivability
    • Field trials and standards
    • Performance modeling and analysis

    Manuscript Submission

    To submit to this special issue, follow the normal procedure for submission to JON, indicating ``Optical Access Networks feature' in the ``Comments' field of the online submission form. For all other questions relating to this feature issue, please send an e-mail to jon@osa.org, subject line ``Optical Access Networks' Additional information can be found on the JON website: http://www.osa-jon.org/submission/. Submission Deadline: 1 June 2005

  2. Fixed Access Network Sharing

    NASA Astrophysics Data System (ADS)

    Cornaglia, Bruno; Young, Gavin; Marchetta, Antonio

    2015-12-01

    Fixed broadband network deployments are moving inexorably to the use of Next Generation Access (NGA) technologies and architectures. These NGA deployments involve building fiber infrastructure increasingly closer to the customer in order to increase the proportion of fiber on the customer's access connection (Fibre-To-The-Home/Building/Door/Cabinet… i.e. FTTx). This increases the speed of services that can be sold and will be increasingly required to meet the demands of new generations of video services as we evolve from HDTV to "Ultra-HD TV" with 4k and 8k lines of video resolution. However, building fiber access networks is a costly endeavor. It requires significant capital in order to cover any significant geographic coverage. Hence many companies are forming partnerships and joint-ventures in order to share the NGA network construction costs. One form of such a partnership involves two companies agreeing to each build to cover a certain geographic area and then "cross-selling" NGA products to each other in order to access customers within their partner's footprint (NGA coverage area). This is tantamount to a bi-lateral wholesale partnership. The concept of Fixed Access Network Sharing (FANS) is to address the possibility of sharing infrastructure with a high degree of flexibility for all network operators involved. By providing greater configuration control over the NGA network infrastructure, the service provider has a greater ability to define the network and hence to define their product capabilities at the active layer. This gives the service provider partners greater product development autonomy plus the ability to differentiate from each other at the active network layer.

  3. Digital Social Network Mining for Topic Discovery

    NASA Astrophysics Data System (ADS)

    Moradianzadeh, Pooya; Mohi, Maryam; Sadighi Moshkenani, Mohsen

    Networked computers are expanding more and more around the world, and digital social networks becoming of great importance for many people's work and leisure. This paper mainly focused on discovering the topic of exchanging information in digital social network. In brief, our method is to use a hierarchical dictionary of related topics and words that mapped to a graph. Then, with comparing the extracted keywords from the context of social network with graph nodes, probability of relation between context and desired topics will be computed. This model can be used in many applications such as advertising, viral marketing and high-risk group detection.

  4. A quantum access network.

    PubMed

    Fröhlich, Bernd; Dynes, James F; Lucamarini, Marco; Sharpe, Andrew W; Yuan, Zhiliang; Shields, Andrew J

    2013-09-01

    The theoretically proven security of quantum key distribution (QKD) could revolutionize the way in which information exchange is protected in the future. Several field tests of QKD have proven it to be a reliable technology for cryptographic key exchange and have demonstrated nodal networks of point-to-point links. However, until now no convincing answer has been given to the question of how to extend the scope of QKD beyond niche applications in dedicated high security networks. Here we introduce and experimentally demonstrate the concept of a 'quantum access network': based on simple and cost-effective telecommunication technologies, the scheme can greatly expand the number of users in quantum networks and therefore vastly broaden their appeal. We show that a high-speed single-photon detector positioned at a network node can be shared between up to 64 users for exchanging secret keys with the node, thereby significantly reducing the hardware requirements for each user added to the network. This point-to-multipoint architecture removes one of the main obstacles restricting the widespread application of QKD. It presents a viable method for realizing multi-user QKD networks with efficient use of resources, and brings QKD closer to becoming a widespread technology. PMID:24005413

  5. Current topics on vascular access for hemodialysis.

    PubMed

    Tordoir, J H M; Van Der Sande, F M; De Haan, M W

    2004-09-01

    Vascular access remains the lifeline for end-stage renal failure patients, which have been treated by chronic intermittent hemodialysis. Due to the steady increase in the number of patients with difficulties to create access, in particular in elderly with various comorbidities, the need for more insight and regulations have evolved into the publications of the American and European guidelines. From the latter it may be obvious that an adequate preoperative assessment followed by the creation of autogenous arteriovenous fistulas (AVFs) is far better and preferred to the implantation of grafts. Vascular access maintenance by monitoring and elective percutanuous or surgical revision is of utmost importance to keep the access site functional. Despite up-to-date measures for vascular access maintenance, various complications may treaten not only the access site but also quality and expectance of life. Thrombotic occlusion remains a major event, leading to permanent failure in 10% of AVFs and 20% of grafts each year. Interventional (percutaneous transluminal angioplasty and/or stent implantation) or surgical revision of thrombosed accesses have similar outcomes with a high rate of reinterventions. The elderly diabetic population with peripheral arteriosclerotic obstructive disease is in particular prone to angio-access induced handischemia. When not timely and properly treated this may lead to minor or major amputation, further hampering quality of life. Also, the enormous application in the past 2 decades of acute central venous lines has lead to a significant increase of central venous obstruction with concomittent morbidity and problems creating vascular access in the upper extremities. Radiological intervention in these cases is a primary option, leaving surgical reconstruction as a second best method. It may be obvious that creation and maintenance of hemodialysis vascular access has become an important and time-consuming speciality. Only an up

  6. Editorial: Next Generation Access Networks

    NASA Astrophysics Data System (ADS)

    Ruffini, Marco; Cincotti, Gabriella; Pizzinat, Anna; Vetter, Peter

    2015-12-01

    Over the past decade we have seen an increasing number of operators deploying Fibre-to-the-home (FTTH) solutions in access networks, in order to provide home users with a much needed network access upgrade, to support higher peak rates, higher sustained rates and a better and more uniform broadband coverage of the territory.

  7. Making Advanced Computer Science Topics More Accessible through Interactive Technologies

    ERIC Educational Resources Information Center

    Shao, Kun; Maher, Peter

    2012-01-01

    Purpose: Teaching advanced technical concepts in a computer science program to students of different technical backgrounds presents many challenges. The purpose of this paper is to present a detailed experimental pedagogy in teaching advanced computer science topics, such as computer networking, telecommunications and data structures using…

  8. Broadband Access Network Planning Optimization Considering Real Copper Cable Lengths

    NASA Astrophysics Data System (ADS)

    Peternel, Blaž Kos, Andrej

    Broadband access network planning strategies with techno-economic calculations are important topics, when optimal broadband network deployments are considered. This paper analyzes optimal deployment combination of digital subscriber line technologies (xDSL) and fiber to the home technologies (FTTx), following different user bandwidth demand scenarios. For this reason, optimal placement of remote digital subscriber line multiplexer (RDSLAM) is examined. Furthermore, the article also discusses the economy of investments, depending on certain investment threshold and the reach of different xDSL technologies. Finally, the difference between broadband network deployment in a characteristic urban and rural area in Republic of Slovenia, in terms of required optical cable dig length per household is shown. A tree structure network model of a traditional copper access network is introduced. A dynamic programming logic, with recursion as a basis of a tree structure examination and evaluation of optimal network elements placement is used. The tree structure network model considers several real network parameters (e. g.: copper cable lengths, user coordinates, node coordinates). The main input for the optimization is a local loop distance between each user and a candidate node for RDSLAM placement. Modelling of copper access networks with a tree structure makes new extensions in planning optimization of broadband access networks. Optimization of network elements placement has direct influence on efficiency and profitability of broadband access telecommunication networks.

  9. Multiple access mass storage network

    SciTech Connect

    Wentz, D.L. Jr.

    1980-01-01

    The Multi-Access Storage Subnetwork (MASS) is the latest addition to the Octopus computer network at Lawrence Livermore Laboratory. The subnetwork provides shared mass storage for the Laboratory's multiple-host computer configuration. A Control Data Corp. 38500 Mass Storage facility is interfaces by MASS to the large, scientific worker computers to provide an on-line capacity of 1 trillion bits of user-accessible data. The MASS architecture offers a very high performance approach to the management of large data storage, as well as a high degree of reliability needed for operation in the Laboratory's timesharing environment. MASS combines state-of-the-art digital hardware with an innovative system philosophy. The key LLL design features of the subnetwork that contribute to the high performance include the following: a data transmission scheme that provides a 40-Mbit/s channel over distances of up to 1000 ft, a large metal-oxide-semiconductor (MOS) memory buffer controlled by a 24-port memory multiplexer with an aggregate data rate of 280 Mbit/s, and a set of high-speed microprocessor-based controllers driving the commercial mass storage units. Reliability of the system is provided by a completely redundant network, including two control minicomputer systems. Also enhancing reliability is error detection and correction in the MOS memory. A hardware-generated checksum is carried with each file throughout the entire network to ensure integrity of user files. 6 figures, 1 table.

  10. Multi-Topic Tracking Model for dynamic social network

    NASA Astrophysics Data System (ADS)

    Li, Yuhua; Liu, Changzheng; Zhao, Ming; Li, Ruixuan; Xiao, Hailing; Wang, Kai; Zhang, Jun

    2016-07-01

    The topic tracking problem has attracted much attention in the last decades. However, existing approaches rarely consider network structures and textual topics together. In this paper, we propose a novel statistical model based on dynamic bayesian network, namely Multi-Topic Tracking Model for Dynamic Social Network (MTTD). It takes influence phenomenon, selection phenomenon, document generative process and the evolution of textual topics into account. Specifically, in our MTTD model, Gibbs Random Field is defined to model the influence of historical status of users in the network and the interdependency between them in order to consider the influence phenomenon. To address the selection phenomenon, a stochastic block model is used to model the link generation process based on the users' interests to topics. Probabilistic Latent Semantic Analysis (PLSA) is used to describe the document generative process according to the users' interests. Finally, the dependence on the historical topic status is also considered to ensure the continuity of the topic itself in topic evolution model. Expectation Maximization (EM) algorithm is utilized to estimate parameters in the proposed MTTD model. Empirical experiments on real datasets show that the MTTD model performs better than Popular Event Tracking (PET) and Dynamic Topic Model (DTM) in generalization performance, topic interpretability performance, topic content evolution and topic popularity evolution performance.

  11. Equalizing Access to Electronic Networked Resources: A Model for Rural Libraries in the United States.

    ERIC Educational Resources Information Center

    Senkevitch, Judith J.; Wolfram, Dietmar

    1994-01-01

    Provides an overview of the current state of networking technology in rural libraries and describes a model for educating rural librarians in accessing electronic networks. Topics discussed include information needs in rural libraries; telecommunications technology access in rural areas; and examples of services to enhance information access.…

  12. Network Access Control List Situation Awareness

    ERIC Educational Resources Information Center

    Reifers, Andrew

    2010-01-01

    Network security is a large and complex problem being addressed by multiple communities. Nevertheless, current theories in networking security appear to overestimate network administrators' ability to understand network access control lists (NACLs), providing few context specific user analyses. Consequently, the current research generally seems to…

  13. Small Satellite Access of the Space Network

    NASA Technical Reports Server (NTRS)

    Horan, Stephen; Minnix, Timothy O.; Vigil, J. S.

    1999-01-01

    Small satellites have been perceived as having limited access to NASA's Space Network (SN). The potential for satellite access of the space network when the design utilizes a fixed antenna configuration and low-power, coded transmission is analyzed. From the analysis, satellites using this configuration in high-inclination orbits are shown to have a daily data throughput in the 100 to 1000 Mbit range using the multiple access communications service.

  14. Recent Progress in Some Active Topics on Complex Networks

    NASA Astrophysics Data System (ADS)

    Gu, J.; Zhu, Y.; Guo, L.; Jiang, J.; Chi, L.; Li, W.; Wang, Q. A.; Cai, X.

    2015-04-01

    Complex networks have been extensively studied across many fields, especially in interdisciplinary areas. It has since long been recognized that topological structures and dynamics are important aspects for capturing the essence of complex networks. The recent years have also witnessed the emergence of several new elements which play important roles in network study. By combining the results of different research orientations in our group, we provide here a review of the recent advances in regards to spectral graph theory, opinion dynamics, interdependent networks, graph energy theory and temporal networks. We hope this will be helpful for the newcomers of those fields to discover new intriguing topics.

  15. Optical access: networks and components (overview)

    NASA Astrophysics Data System (ADS)

    Mynbaev, Djafar K.

    2004-09-01

    The exponential gtowth of traffic delivered to an individual customer both for business and personal needs puts tremendous pressure on the telecommunications networks. Because the development of the long-haul and metro networks has advanced rapidly and their capacity much eceeds demand, tremendous pressure now falls in the local networks to provide customers with access to the global telecom infrastructure. Building a broadband access network enabling fast delivery of high-volume traffic is the current task of network operators. A brief review of broadband access networks brings us to the conclusion that only wired optical networks can serve as an immediate and future solution to the "last-mile" problem. After discussin goptical access network classification, we focus mainly on passive optical networks (PON) because PON is a major technology today. From the network standpoint, we discuss the principle of PON operation, architectures, topologies, protocols and standards, design issues, and network management and services. We also discuss the main problems with PON and the use of WDM technology. From the hardware standpoint, we consider both active and passive components. We analyze the structure and elements of these components, including their technical characteristics.

  16. Integrating Emerging Topics through Online Team Design in a Hybrid Communication Networks Course: Interaction Patterns and Impact of Prior Knowledge

    ERIC Educational Resources Information Center

    Reisslein, Jana; Seeling, Patrick; Reisslein, Martin

    2005-01-01

    An important challenge in the introductory communication networks course in electrical and computer engineering curricula is to integrate emerging topics, such as wireless Internet access and network security, into the already content-intensive course. At the same time it is essential to provide students with experiences in online collaboration,…

  17. Topic segmentation via community detection in complex networks.

    PubMed

    de Arruda, Henrique F; Costa, Luciano da F; Amancio, Diego R

    2016-06-01

    Many real systems have been modeled in terms of network concepts, and written texts are a particular example of information networks. In recent years, the use of network methods to analyze language has allowed the discovery of several interesting effects, including the proposition of novel models to explain the emergence of fundamental universal patterns. While syntactical networks, one of the most prevalent networked models of written texts, display both scale-free and small-world properties, such a representation fails in capturing other textual features, such as the organization in topics or subjects. We propose a novel network representation whose main purpose is to capture the semantical relationships of words in a simple way. To do so, we link all words co-occurring in the same semantic context, which is defined in a threefold way. We show that the proposed representations favor the emergence of communities of semantically related words, and this feature may be used to identify relevant topics. The proposed methodology to detect topics was applied to segment selected Wikipedia articles. We found that, in general, our methods outperform traditional bag-of-words representations, which suggests that a high-level textual representation may be useful to study the semantical features of texts. PMID:27368785

  18. Topic segmentation via community detection in complex networks

    NASA Astrophysics Data System (ADS)

    de Arruda, Henrique F.; Costa, Luciano da F.; Amancio, Diego R.

    2016-06-01

    Many real systems have been modeled in terms of network concepts, and written texts are a particular example of information networks. In recent years, the use of network methods to analyze language has allowed the discovery of several interesting effects, including the proposition of novel models to explain the emergence of fundamental universal patterns. While syntactical networks, one of the most prevalent networked models of written texts, display both scale-free and small-world properties, such a representation fails in capturing other textual features, such as the organization in topics or subjects. We propose a novel network representation whose main purpose is to capture the semantical relationships of words in a simple way. To do so, we link all words co-occurring in the same semantic context, which is defined in a threefold way. We show that the proposed representations favor the emergence of communities of semantically related words, and this feature may be used to identify relevant topics. The proposed methodology to detect topics was applied to segment selected Wikipedia articles. We found that, in general, our methods outperform traditional bag-of-words representations, which suggests that a high-level textual representation may be useful to study the semantical features of texts.

  19. Planning Multitechnology Access Networks with Performance Constraints

    NASA Astrophysics Data System (ADS)

    Chamberland, Steven

    Considering the number of access network technologies and the investment needed for the “last mile” of a solution, in today’s highly competitive markets, planning tools are crucial for the service providers to optimize the network costs and accelerate the planning process. In this paper, we propose to tackle the problem of planning access networks composed of four technologies/architectures: the digital subscriber line (xDSL) technologies deployed directly from the central office (CO), the fiber-to-the-node (FTTN), the fiber-to-the-micro-node (FTTn) and the fiber-to-the-premises (FTTP). A mathematical programming model is proposed for this planning problem that is solved using a commercial implementation of the branch-and-bound algorithm. Next, a detailed access network planning example is presented followed by a systematic set of experiments designed to assess the performance of the proposed approach.

  20. Quantum secured gigabit optical access networks

    NASA Astrophysics Data System (ADS)

    Fröhlich, Bernd; Dynes, James F.; Lucamarini, Marco; Sharpe, Andrew W.; Tam, Simon W.-B.; Yuan, Zhiliang; Shields, Andrew J.

    2015-12-01

    Optical access networks connect multiple endpoints to a common network node via shared fibre infrastructure. They will play a vital role to scale up the number of users in quantum key distribution (QKD) networks. However, the presence of power splitters in the commonly used passive network architecture makes successful transmission of weak quantum signals challenging. This is especially true if QKD and data signals are multiplexed in the passive network. The splitter introduces an imbalance between quantum signal and Raman noise, which can prevent the recovery of the quantum signal completely. Here we introduce a method to overcome this limitation and demonstrate coexistence of multi-user QKD and full power data traffic from a gigabit passive optical network (GPON) for the first time. The dual feeder implementation is compatible with standard GPON architectures and can support up to 128 users, highlighting that quantum protected GPON networks could be commonplace in the future.

  1. Quantum secured gigabit optical access networks

    PubMed Central

    Fröhlich, Bernd; Dynes, James F.; Lucamarini, Marco; Sharpe, Andrew W.; Tam, Simon W.-B.; Yuan, Zhiliang; Shields, Andrew J.

    2015-01-01

    Optical access networks connect multiple endpoints to a common network node via shared fibre infrastructure. They will play a vital role to scale up the number of users in quantum key distribution (QKD) networks. However, the presence of power splitters in the commonly used passive network architecture makes successful transmission of weak quantum signals challenging. This is especially true if QKD and data signals are multiplexed in the passive network. The splitter introduces an imbalance between quantum signal and Raman noise, which can prevent the recovery of the quantum signal completely. Here we introduce a method to overcome this limitation and demonstrate coexistence of multi-user QKD and full power data traffic from a gigabit passive optical network (GPON) for the first time. The dual feeder implementation is compatible with standard GPON architectures and can support up to 128 users, highlighting that quantum protected GPON networks could be commonplace in the future. PMID:26656307

  2. Building new access network using reconfigurable optical grid network and wireless network

    NASA Astrophysics Data System (ADS)

    Qiu, Yinghui; Wu, Runze; Ji, Yuefeng; Xu, Daxiong

    2007-11-01

    Recently wireless mesh network has been gaining increasing attention and early versions are being deployed as municipal access solutions to eliminate the wired drop to every wireless router at customer premise. In this paper, we propose a novel access network using reconfigurable optical burst switching grid network and wireless mesh network. The proposed access network architecture saves network deployment cost because fiber need not penetrate to each end user. We also propose a hierarchical routing protocol to enhance the routing efficiency.

  3. File access prediction using neural networks.

    PubMed

    Patra, Prashanta Kumar; Sahu, Muktikanta; Mohapatra, Subasish; Samantray, Ronak Kumar

    2010-06-01

    One of the most vexing issues in design of a high-speed computer is the wide gap of access times between the memory and the disk. To solve this problem, static file access predictors have been used. In this paper, we propose dynamic file access predictors using neural networks to significantly improve upon the accuracy, success-per-reference, and effective-success-rate-per-reference by using neural-network-based file access predictor with proper tuning. In particular, we verified that the incorrect prediction has been reduced from 53.11% to 43.63% for the proposed neural network prediction method with a standard configuration than the recent popularity (RP) method. With manual tuning for each trace, we are able to improve upon the misprediction rate and effective-success-rate-per-reference using a standard configuration. Simulations on distributed file system (DFS) traces reveal that exact fit radial basis function (RBF) gives better prediction in high end system whereas multilayer perceptron (MLP) trained with Levenberg-Marquardt (LM) backpropagation outperforms in system having good computational capability. Probabilistic and competitive predictors are the most suitable for work stations having limited resources to deal with and the former predictor is more efficient than the latter for servers having maximum system calls. Finally, we conclude that MLP with LM backpropagation algorithm has better success rate of file prediction than those of simple perceptron, last successor, stable successor, and best k out of m predictors.

  4. An access alternative for mobile satellite networks

    NASA Technical Reports Server (NTRS)

    Wu, W. W.

    1988-01-01

    Conceptually, this paper discusses strategies of digital satellite communication networks for a very large number of low density traffic stations. These stations can be either aeronautical, land mobile, or maritime. The techniques can be applied to international, domestic, regional, and special purpose satellite networks. The applications can be commercial, scientific, military, emergency, navigational or educational. The key strategy is the use of a non-orthogonal access method, which tolerates overlapping signals. With n being either time or frequency partitions, and with a single overlapping signal allowed, a low cost mobile satellite system can be designed with n squared (n squared + n + 1) number of terminals.

  5. Expertise finding in bibliographic network: topic dominance learning approach.

    PubMed

    Neshati, Mahmood; Hashemi, Seyyed Hadi; Beigy, Hamid

    2014-12-01

    Expert finding problem in bibliographic networks has received increased interest in recent years. This problem concerns finding relevant researchers for a given topic. Motivated by the observation that rarely do all coauthors contribute to a paper equally, in this paper, we propose two discriminative methods for realizing leading authors contributing in a scientific publication. Specifically, we cast the problem of expert finding in a bibliographic network to find leading experts in a research group, which is easier to solve. We recognize three feature groups that can discriminate relevant experts from other authors of a document. Experimental results on a real dataset, and a synthetic one that is gathered from a Microsoft academic search engine, show that the proposed model significantly improves the performance of expert finding in terms of all common information retrieval evaluation metrics.

  6. Optical solutions for unbundled access network

    NASA Astrophysics Data System (ADS)

    Bacîş Vasile, Irina Bristena

    2015-02-01

    The unbundling technique requires finding solutions to guarantee the economic and technical performances imposed by the nature of the services that can be offered. One of the possible solutions is the optic one; choosing this solution is justified for the following reasons: it optimizes the use of the access network, which is the most expensive part of a network (about 50% of the total investment in telecommunications networks) while also being the least used (telephone traffic on the lines has a low cost); it increases the distance between the master station/central and the terminal of the subscriber; the development of the services offered to the subscribers is conditioned by the subscriber network. For broadband services there is a need for support for the introduction of high-speed transport. A proper identification of the factors that must be satisfied and a comprehensive financial evaluation of all resources involved, both the resources that are in the process of being bought as well as extensions are the main conditions that would lead to a correct choice. As there is no single optimal technology for all development scenarios, which can take into account all access systems, a successful implementation is always done by individual/particularized scenarios. The method used today for the selection of an optimal solution is based on statistics and analysis of the various, already implemented, solutions, and on the experience that was already gained; the main evaluation criterion and the most unbiased one is the ratio between the cost of the investment and the quality of service, while serving an as large as possible number of customers.

  7. Optical networks, last mile access and applications

    NASA Astrophysics Data System (ADS)

    Leitgeb, E.; Gebhart, M.; Birnbacher, U.

    topology, reliability and availability. The advantages and disadvantages of different FSO technologies, as well as the backbone technology are discussed in this respect. Furthermore, the last mile access using FSO will be investigated for different environment areas (e.g., urban, rural, mountain) and climate zones. The availability of the FSO link is mainly determined by the local atmospheric conditions and distance and will be examined for the last mile. Results of various studies will complete these investigations. Finally, an example for realizing a FSO network for the last mile will be shown. In this example FSO transmitters with light emitting diodes (LED) instead of laser diodes will be described. By using LEDs, problems with laser-and eye safety are minimized. Some multimedia applications (like video-conferences, live TV-transmissions, etc.) will illustrate the range of applications for FSO last mile networks.

  8. Sierra Stars Observatory Network: An Accessible Global Network

    NASA Astrophysics Data System (ADS)

    Williams, Richard; Beshore, Edward

    2011-03-01

    The Sierra Stars Observatory Network (SSON) is a unique partnership among professional observatories that provides its users with affordable high-quality calibrated image data. SSON comprises observatories in the Northern and Southern Hemisphere and is in the process of expanding to a truly global network capable of covering the entire sky 24 hours a day in the near future. The goal of SSON is to serve the needs of science-based projects and programs. Colleges, universities, institutions, and individuals use SSON for their education and research projects. The mission of SSON is to promote and expand the use of its facilities among the thousands of colleges and schools worldwide that do not have access to professional-quality automated observatory systems to use for astronomy education and research. With appropriate leadership and guidance educators can use SSON to help teach astronomy and do meaningful scientific projects. The relatively small cost of using SSON for this type of work makes it affordable and accessible for educators to start using immediately. Remote observatory services like SSON need to evolve to better support education and research initiatives of colleges, institutions and individual investigators. To meet these needs, SSON is developing a sophisticated interactive scheduling system to integrate among the nodes of the observatory network. This will enable more dynamic observations, including immediate priority interrupts, acquiring moving objects using ephemeris data, and more.

  9. Scalable Lunar Surface Networks and Adaptive Orbit Access

    NASA Technical Reports Server (NTRS)

    Wang, Xudong

    2015-01-01

    Teranovi Technologies, Inc., has developed innovative network architecture, protocols, and algorithms for both lunar surface and orbit access networks. A key component of the overall architecture is a medium access control (MAC) protocol that includes a novel mechanism of overlaying time division multiple access (TDMA) and carrier sense multiple access with collision avoidance (CSMA/CA), ensuring scalable throughput and quality of service. The new MAC protocol is compatible with legacy Institute of Electrical and Electronics Engineers (IEEE) 802.11 networks. Advanced features include efficiency power management, adaptive channel width adjustment, and error control capability. A hybrid routing protocol combines the advantages of ad hoc on-demand distance vector (AODV) routing and disruption/delay-tolerant network (DTN) routing. Performance is significantly better than AODV or DTN and will be particularly effective for wireless networks with intermittent links, such as lunar and planetary surface networks and orbit access networks.

  10. Future Service Adaptive Access/Aggregation Network Architecture

    NASA Astrophysics Data System (ADS)

    Ikeda, Hiroki; Takeshita, Hidetoshi; Okamoto, Satoru

    The emergence of new services in the cloud computing era has made smooth service migration an important issue in access networks. However, different types of equipment are typically used for the different services due to differences in service requirements. This leads to an increase in not only capital expenditures but also operational expenditures. Here we propose using a service adaptive approach as a solution to this problem. We analyze the requirements of a future access network in terms of service, network, and node. We discuss available access network technologies including the passive optical network, single star network. Finally, we present a future service adaptive access/aggregation network and its architecture along with a programmable optical line terminal and optical network unit, discuss its benefit, and describe example services that it would support.

  11. 47 CFR 36.213 - Network access services revenues.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Network access services revenues. 36.213 Section 36.213 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES... Income Accounts Operating Revenues § 36.213 Network access services revenues. (a) End User...

  12. 47 CFR 36.213 - Network access services revenues.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Network access services revenues. 36.213 Section 36.213 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES... Income Accounts Operating Revenues § 36.213 Network access services revenues. (a) End User...

  13. Topic Models for Link Prediction in Document Networks

    ERIC Educational Resources Information Center

    Kataria, Saurabh

    2012-01-01

    Recent explosive growth of interconnected document collections such as citation networks, network of web pages, content generated by crowd-sourcing in collaborative environments, etc., has posed several challenging problems for data mining and machine learning community. One central problem in the domain of document networks is that of "link…

  14. Effects of network node consolidation in optical access and aggregation networks on costs and power consumption

    NASA Astrophysics Data System (ADS)

    Lange, Christoph; Hülsermann, Ralf; Kosiankowski, Dirk; Geilhardt, Frank; Gladisch, Andreas

    2010-01-01

    The increasing demand for higher bit rates in access networks requires fiber deployment closer to the subscriber resulting in fiber-to-the-home (FTTH) access networks. Besides higher access bit rates optical access network infrastructure and related technologies enable the network operator to establish larger service areas resulting in a simplified network structure with a lower number of network nodes. By changing the network structure network operators want to benefit from a changed network cost structure by decreasing in short and mid term the upfront investments for network equipment due to concentration effects as well as by reducing the energy costs due to a higher energy efficiency of large network sites housing a high amount of network equipment. In long term also savings in operational expenditures (OpEx) due to the closing of central office (CO) sites are expected. In this paper different architectures for optical access networks basing on state-of-the-art technology are analyzed with respect to network installation costs and power consumption in the context of access node consolidation. Network planning and dimensioning results are calculated for a realistic network scenario of Germany. All node consolidation scenarios are compared against a gigabit capable passive optical network (GPON) based FTTH access network operated from the conventional CO sites. The results show that a moderate reduction of the number of access nodes may be beneficial since in that case the capital expenditures (CapEx) do not rise extraordinarily and savings in OpEx related to the access nodes are expected. The total power consumption does not change significantly with decreasing number of access nodes but clustering effects enable a more energyefficient network operation and optimized power purchase order quantities leading to benefits in energy costs.

  15. Ethernet access network based on free-space optic deployment technology

    NASA Astrophysics Data System (ADS)

    Gebhart, Michael; Leitgeb, Erich; Birnbacher, Ulla; Schrotter, Peter

    2004-06-01

    The satisfaction of all communication needs from single households and business companies over a single access infrastructure is probably the most challenging topic in communications technology today. But even though the so-called "Last Mile Access Bottleneck" is well known since more than ten years and many distribution technologies have been tried out, the optimal solution has not yet been found and paying commercial access networks offering all service classes are still rare today. Conventional services like telephone, radio and TV, as well as new and emerging services like email, web browsing, online-gaming, video conferences, business data transfer or external data storage can all be transmitted over the well known and cost effective Ethernet networking protocol standard. Key requirements for the deployment technology driven by the different services are high data rates to the single customer, security, moderate deployment costs and good scalability to number and density of users, quick and flexible deployment without legal impediments and high availability, referring to the properties of optical and wireless communication. We demonstrate all elements of an Ethernet Access Network based on Free Space Optic distribution technology. Main physical parts are Central Office, Distribution Network and Customer Equipment. Transmission of different services, as well as configuration, service upgrades and remote control of the network are handled by networking features over one FSO connection. All parts of the network are proven, the latest commercially available technology. The set up is flexible and can be adapted to any more specific need if required.

  16. Fiber Access Networks: Reliability Analysis and Swedish Broadband Market

    NASA Astrophysics Data System (ADS)

    Wosinska, Lena; Chen, Jiajia; Larsen, Claus Popp

    Fiber access network architectures such as active optical networks (AONs) and passive optical networks (PONs) have been developed to support the growing bandwidth demand. Whereas particularly Swedish operators prefer AON, this may not be the case for operators in other countries. The choice depends on a combination of technical requirements, practical constraints, business models, and cost. Due to the increasing importance of reliable access to the network services, connection availability is becoming one of the most crucial issues for access networks, which should be reflected in the network owner's architecture decision. In many cases protection against failures is realized by adding backup resources. However, there is a trade off between the cost of protection and the level of service reliability since improving reliability performance by duplication of network resources (and capital expenditures CAPEX) may be too expensive. In this paper we present the evolution of fiber access networks and compare reliability performance in relation to investment and management cost for some representative cases. We consider both standard and novel architectures for deployment in both sparsely and densely populated areas. While some recent works focused on PON protection schemes with reduced CAPEX the current and future effort should be put on minimizing the operational expenditures (OPEX) during the access network lifetime.

  17. Easy Access: Auditing the System Network

    ERIC Educational Resources Information Center

    Wiech, Dean

    2013-01-01

    In today's electronic learning environment, access to appropriate systems and data is of the utmost importance to students, faculty, and staff. Without proper access to the school's internal systems, teachers could be prevented from logging on to an online learning system and students might be unable to submit course work to an online…

  18. An economic analysis on optical Ethernet in the access network

    NASA Astrophysics Data System (ADS)

    Kim, Sung Hwi; Nam, Dohyun; Yoo, Gunil; Kim, WoonHa

    2004-04-01

    Nowadays, Broadband service subscribers have increased exponentially and have almost saturated in Korea. Several types of solutions for broadband service applied to the field. Among several types of broadband services, most of subscribers provided xDSL service like ADSL or VDSL. Usually, they who live in an apartment provided Internet service by Ntopia network as FTTC structure that is a dormant network in economical view at KT. Under competitive telecom environment for new services like video, we faced with needing to expand or rebuild portions of our access networks, are looking for ways to provide any service that competitors might offer presently or in the near future. In order to look for new business model like FTTH service, we consider deploying optical access network. In spite of numerous benefits of PON until now, we cannot believe that PON is the best solution in Korea. Because we already deployed optical access network of ring type feeder cable and have densely population of subscribers that mainly distributed inside 6km from central office. So we try to utilize an existing Ntopia network for FTTH service under optical access environment. Despite of such situations, we try to deploy PON solution in the field as FTTC or FTTH architecture. Therefore we analyze PON structure in comparison with AON structure in order to look for optimized structure in Korea. At first, we describe the existing optical access networks and network architecture briefly. Secondly we investigate the cost of building optical access networks by modeling cost functions on AON and PON structure which based on Ethernet protocol, and analyze two different network architectures according to different deployment scenarios: Urban, small town, rural. Finally we suggest the economic and best solution with PON structure to optimize to optical access environment of KT.

  19. Network access to PCDS (SPAN, ESN, SESNET, ARPANET)

    NASA Technical Reports Server (NTRS)

    Green, J.

    1986-01-01

    One of the major goals of the National Space Science Data Center is to increase access to NASA data systems by enhancing networking activities. The activities are centered around three basic networking systems: the Space Physics Analysis Network (SPAN); the Earth Science Network (ESN); and the NASA Packet Switched System (NPSS). Each system is described, linkages among systems are explained, and future plans are announced. The inclusion of several new climate nodes on SPAN or ESN are also mentioned. Presently, the Pilot Climate Data System is accessible through SPAN and will be accessible through NPSS by summer and ESN by the end of 1986. Ambitious plans for implementation are underway. The implementation of these plans will represent a major advance in the utilization and accessibility of data worldwide.

  20. User Procedures Standardization for Network Access. NBS Technical Note 799.

    ERIC Educational Resources Information Center

    Neumann, A. J.

    User access procedures to information systems have become of crucial importance with the advent of computer networks, which have opened new types of resources to a broad spectrum of users. This report surveys user access protocols of six representative systems: BASIC, GE MK II, INFONET, MEDLINE, NIC/ARPANET and SPIRES. Functional access…

  1. Accessibility and Integrity of Networked Information Collections. Background Paper.

    ERIC Educational Resources Information Center

    Lynch, Clifford A.

    This paper considers questions related to the integrity and accessibility of new electronic information resources. It begins with a review of recent developments in networked information resources and the tools to identify, navigate, and use such resources. An overview is then given of the issues involved in access and integrity questions. Links…

  2. Challenges of future converged access and metro networks

    NASA Astrophysics Data System (ADS)

    Breuer, D.; Hülsermann, R.; Lange, C.; Weis, E.

    2010-01-01

    Steadily increasing customer demand for more and more bandwidth in excess of 100 Mbit/s per subscriber, new technical options and a strong competitive environment drive the evolution of today's telecommunication networks, particularly in the access network. The physical properties of fibers such as very low loss and almost unlimited bandwidth allow for high bit rate long distance transmission in future access networks compared to the conventional copper based access networks in place today. In future this is expected to lead to much larger service areas which are served from one central office and to a significant reduction of central offices of today's infrastructure facilitating a converged metro-access architecture. One driver for this network consolidation is the need for significant operational expenditure (OpEx) savings which are expected due to reduction of active equipment and footprint. But also the changes from today's "service oriented" network design, where each service is almost realized on a new platform, towards an open standardized multi-layer Next Generation Network where all services will be delivered over a common infrastructure will lead to significant challenges in the network infrastructure.

  3. Broadband passive optical network media access control protocols

    NASA Astrophysics Data System (ADS)

    Quayle, Alan

    1996-11-01

    Most telecommunication operators are currently deciding on how to respond to customers' needs stimulated by the synergy between compression coding of multimedia and the emergence of broadband digital networks. This paper describes a range of broadband access architectures under consideration in the full services access network initiative. All architectures have a common requirement for a broadband ATM PON. A common broadband PON applicable to many operators increases the world-wide market for the product. With greater production volumes manufacturers' costs reduce because of the experience curve effect making broadband access systems economic.

  4. Auditing medical records accesses via healthcare interaction networks.

    PubMed

    Chen, You; Nyemba, Steve; Malin, Bradley

    2012-01-01

    Healthcare organizations are deploying increasingly complex clinical information systems to support patient care. Traditional information security practices (e.g., role-based access control) are embedded in enterprise-level systems, but are insufficient to ensure patient privacy. This is due, in part, to the dynamic nature of healthcare, which makes it difficult to predict which care providers need access to what and when. In this paper, we show that modeling operations at a higher level of granularity (e.g., the departmental level) are stable in the context of a relational network, which may enable more effective auditing strategies. We study three months of access logs from a large academic medical center to illustrate that departmental interaction networks exhibit certain invariants, such as the number, strength, and reciprocity of relationships. We further show that the relations extracted from the network can be leveraged to assess the extent to which a patient's care satisfies expected organizational behavior.

  5. Auditing Medical Records Accesses via Healthcare Interaction Networks

    PubMed Central

    Chen, You; Nyemba, Steve; Malin, Bradley

    2012-01-01

    Healthcare organizations are deploying increasingly complex clinical information systems to support patient care. Traditional information security practices (e.g., role-based access control) are embedded in enterprise-level systems, but are insufficient to ensure patient privacy. This is due, in part, to the dynamic nature of healthcare, which makes it difficult to predict which care providers need access to what and when. In this paper, we show that modeling operations at a higher level of granularity (e.g., the departmental level) are stable in the context of a relational network, which may enable more effective auditing strategies. We study three months of access logs from a large academic medical center to illustrate that departmental interaction networks exhibit certain invariants, such as the number, strength, and reciprocity of relationships. We further show that the relations extracted from the network can be leveraged to assess the extent to which a patient’s care satisfies expected organizational behavior. PMID:23304277

  6. An evaluation of Access Tier local area network switches.

    SciTech Connect

    Eldridge, John M.; Olsberg, Ronald R.

    2004-06-01

    This reports tabulates the Test and Evaluation results of the Access Class Switch tests conducted by members of Department 9336. About 15 switches were reviewed for use in the enterprise network as access tier switches as defined in a three tier architecture. The Access Switch Tier has several functions including: aggregate customer desktop ports, preserve and apply QoS tags, provide switched LAN access, provide VLAN assignment, as well as others. The typical switch size is 48 or less user ports. The evaluation team reviewed network switch evaluation reports from the Tolly Group as well as other sources. We then used these reports as a starting point to identify particular switches for evaluation. In general we reviewed the products of dominant equipment manufacturers. Also, based on architectural design requirements, the majority of the switches tested were of relatively small monolithic unit variety.

  7. Phenotype accessibility and noise in random threshold gene regulatory networks.

    PubMed

    Pinho, Ricardo; Garcia, Victor; Feldman, Marcus W

    2014-01-01

    Evolution requires phenotypic variation in a population of organisms for selection to function. Gene regulatory processes involved in organismal development affect the phenotypic diversity of organisms. Since only a fraction of all possible phenotypes are predicted to be accessed by the end of development, organisms may evolve strategies to use environmental cues and noise-like fluctuations to produce additional phenotypic diversity, and hence to enhance the speed of adaptation. We used a generic model of organismal development --gene regulatory networks-- to investigate how different levels of noise on gene expression states (i.e. phenotypes) may affect access to new, unique phenotypes, thereby affecting phenotypic diversity. We studied additional strategies that organisms might adopt to attain larger phenotypic diversity: either by augmenting their genome or the number of gene expression states. This was done for different types of gene regulatory networks that allow for distinct levels of regulatory influence on gene expression or are more likely to give rise to stable phenotypes. We found that if gene expression is binary, increasing noise levels generally decreases phenotype accessibility for all network types studied. If more gene expression states are considered, noise can moderately enhance the speed of discovery if three or four gene expression states are allowed, and if there are enough distinct regulatory networks in the population. These results were independent of the network types analyzed, and were robust to different implementations of noise. Hence, for noise to increase the number of accessible phenotypes in gene regulatory networks, very specific conditions need to be satisfied. If the number of distinct regulatory networks involved in organismal development is large enough, and the acquisition of more genes or fine tuning of their expression states proves costly to the organism, noise can be useful in allowing access to more unique phenotypes

  8. Phenotype Accessibility and Noise in Random Threshold Gene Regulatory Networks

    PubMed Central

    Feldman, Marcus W.

    2015-01-01

    Evolution requires phenotypic variation in a population of organisms for selection to function. Gene regulatory processes involved in organismal development affect the phenotypic diversity of organisms. Since only a fraction of all possible phenotypes are predicted to be accessed by the end of development, organisms may evolve strategies to use environmental cues and noise-like fluctuations to produce additional phenotypic diversity, and hence to enhance the speed of adaptation. We used a generic model of organismal development --gene regulatory networks-- to investigate how different levels of noise on gene expression states (i.e. phenotypes) may affect access to new, unique phenotypes, thereby affecting phenotypic diversity. We studied additional strategies that organisms might adopt to attain larger phenotypic diversity: either by augmenting their genome or the number of gene expression states. This was done for different types of gene regulatory networks that allow for distinct levels of regulatory influence on gene expression or are more likely to give rise to stable phenotypes. We found that if gene expression is binary, increasing noise levels generally decreases phenotype accessibility for all network types studied. If more gene expression states are considered, noise can moderately enhance the speed of discovery if three or four gene expression states are allowed, and if there are enough distinct regulatory networks in the population. These results were independent of the network types analyzed, and were robust to different implementations of noise. Hence, for noise to increase the number of accessible phenotypes in gene regulatory networks, very specific conditions need to be satisfied. If the number of distinct regulatory networks involved in organismal development is large enough, and the acquisition of more genes or fine tuning of their expression states proves costly to the organism, noise can be useful in allowing access to more unique phenotypes

  9. High speed OFDM-CDMA optical access network.

    PubMed

    Guo, X; Wang, Q; Zhou, L; Fang, L; Wonfor, A; Penty, R V; White, I H

    2016-04-15

    We demonstrate the feasibility of a 16 × 3.75 Gb/s (60 Gb/s aggregate) Orthogonal frequency division multiplexing-code division multiple access passive optical network for next-generation access applications. 3.75 Gb/s PON channel transmission over 25 km single-mode fiber shows 0.1 dB dispersion and 0.9 dB crosstalk penalties. Advantages of the system include high capacity, enhanced spectral efficiency, coding gain, and networking functions such as increased security and single-wavelength operation.

  10. Dynamic resource allocation in hybrid access femtocell network.

    PubMed

    Ahmed, Afaz Uddin; Islam, Mohammad Tariqul; Ismail, Mahamod; Ghanbarisabagh, Mohammad

    2014-01-01

    Intercell interference is one of the most challenging issues in femtocell deployment under the coverage of existing macrocell. Allocation of resources between femtocell and macrocell is essential to counter the effects of interference in dense femtocell networks. Advances in resource management strategies have improved the control mechanism for interference reduction at lower node density, but most of them are ineffective at higher node density. In this paper, a dynamic resource allocation management algorithm (DRAMA) for spectrum shared hybrid access OFDMA femtocell network is proposed. To reduce the macro-femto-tier interference and to improve the quality of service, the proposed algorithm features a dynamic resource allocation scheme by controlling them both centrally and locally. The proposed scheme focuses on Femtocell Access Point (FAP) owners' satisfaction and allows maximum utilization of available resources based on congestion in the network. A simulation environment is developed to study the quantitative performance of DRAMA in hybrid access-control femtocell network and compare it to closed and open access mechanisms. The performance analysis shows that higher number of random users gets connected to the FAP without compromising FAP owners' satisfaction allowing the macrocell to offload a large number of users in a dense heterogeneous network. PMID:24782662

  11. Proposal of using wireless optical mesh networks and integrated VDSL for broadband access networks

    NASA Astrophysics Data System (ADS)

    Zhang, Jinlong

    2001-11-01

    The proposal addresses the wireless optical broadband access networks architecture by deploying mesh network structure, which could be the alternatives to FTTx (home or node, etc) architecture. Instead of fiber used as the transmission medium in the distribution plant, here we suggest to use the free space optic links to construct the optical mesh network. The practical connections are depending on the services provided. For Video-on-Demand (VoD) service, the final connection could use twisted pair by integrated VDSL technology. The distributed bandwidth can reach 25-32 Mbps per end user. In this paper we give some comments for designing a broadband access network using optical mesh network structure. It includes the traffic estimation, transmission network design and access node design suggestions.

  12. Large optical 3D MEMS switches in access networks

    NASA Astrophysics Data System (ADS)

    Madamopoulos, Nicholas; Kaman, Volkan; Yuan, Shifu; Jerphagnon, Olivier; Helkey, Roger; Bowers, John E.

    2007-09-01

    Interest is high among residential customers and businesses for advanced, broadband services such as fast Internet access, electronic commerce, video-on-demand, digital broadcasting, teleconferencing and telemedicine. In order to satisfy such growing demand of end-customers, access technologies such as fiber-to-the-home/building (FTTH/B) are increasingly being deployed. Carriers can reduce maintenance costs, minimize technology obsolescence and introduce new services easily by reducing active elements in the fiber access network. However, having a passive optical network (PON) also introduces operational and maintenance challenges. Increased diagnostic monitoring capability of the network becomes a necessity as more and more fibers are provisioned to deliver services to the end-customers. This paper demonstrates the clear advantages that large 3D optical MEMS switches offer in solving these access network problems. The advantages in preventative maintenance, remote monitoring, test and diagnostic capability are highlighted. The low optical insertion loss for all switch optical connections of the switch enables the monitoring, grooming and serving of a large number of PON lines and customers. Furthermore, the 3D MEMS switch is transparent to optical wavelengths and data formats, thus making it easy to incorporate future upgrades, such higher bit rates or DWDM overlay to a PON.

  13. Distributed policy based access to networked heterogeneous ISR data sources

    NASA Astrophysics Data System (ADS)

    Bent, G.; Vyvyan, D.; Wood, David; Zerfos, Petros; Calo, Seraphin

    2010-04-01

    Within a coalition environment, ad hoc Communities of Interest (CoI's) come together, perhaps for only a short time, with different sensors, sensor platforms, data fusion elements, and networks to conduct a task (or set of tasks) with different coalition members taking different roles. In such a coalition, each organization will have its own inherent restrictions on how it will interact with the others. These are usually stated as a set of policies, including security and privacy policies. The capability that we want to enable for a coalition operation is to provide access to information from any coalition partner in conformance with the policies of all. One of the challenges in supporting such ad-hoc coalition operations is that of providing efficient access to distributed sources of data, where the applications requiring the data do not have knowledge of the location of the data within the network. To address this challenge the International Technology Alliance (ITA) program has been developing the concept of a Dynamic Distributed Federated Database (DDFD), also know as a Gaian Database. This type of database provides a means for accessing data across a network of distributed heterogeneous data sources where access to the information is controlled by a mixture of local and global policies. We describe how a network of disparate ISR elements can be expressed as a DDFD and how this approach enables sensor and other information sources to be discovered autonomously or semi-autonomously and/or combined, fused formally defined local and global policies.

  14. The CREATE Network (Computer Resource Educational Access in Tennessee Education).

    ERIC Educational Resources Information Center

    Moon, Fletcher F.

    The CREATE Network (Computer Resource Educational Access in Tennessee Education) brought together library professionals from Tennessee's seven historically black colleges and universities (HBCUs) for purposes of training and implementation of library applications of computer-based information technology. Annual training seminars were held at…

  15. Energy challenges in optical access and aggregation networks.

    PubMed

    Kilper, Daniel C; Rastegarfar, Houman

    2016-03-01

    Scalability is a critical issue for access and aggregation networks as they must support the growth in both the size of data capacity demands and the multiplicity of access points. The number of connected devices, the Internet of Things, is growing to the tens of billions. Prevailing communication paradigms are reaching physical limitations that make continued growth problematic. Challenges are emerging in electronic and optical systems and energy increasingly plays a central role. With the spectral efficiency of optical systems approaching the Shannon limit, increasing parallelism is required to support higher capacities. For electronic systems, as the density and speed increases, the total system energy, thermal density and energy per bit are moving into regimes that become impractical to support-for example requiring single-chip processor powers above the 100 W limit common today. We examine communication network scaling and energy use from the Internet core down to the computer processor core and consider implications for optical networks. Optical switching in data centres is identified as a potential model from which scalable access and aggregation networks for the future Internet, with the application of integrated photonic devices and intelligent hybrid networking, will emerge. PMID:26809581

  16. A secure network access system for mobile IPv6

    NASA Astrophysics Data System (ADS)

    Zhang, Hong; Yuan, Man; He, Rui; Jiang, Luliang; Ma, Jian; Qian, Hualin

    2004-03-01

    With the fast development of Internet and wireless and mobile communication technology, the Mobile Internet Age is upcoming. For those providing Mobile Internet services, especially from the view of ISP (Internet Service Provider), current mobile IP protocol is insufficient. Since the Mobile IPv6 protocol will be popular in near future, how to provide a secure mobile IPv6 service is important. A secure mobile IPv6 network access system is highly needed for mobile IPv6 deployment. Current methods and systems are still inadequate, including EAP, PANA, 802.1X, RADIUS, Diameter, etc. In this paper, we describe main security goals for a secure mobile IPv6 access system, and propose a secure network access system to achieve them. This access system consists of access router, attendant and authentication servers. The access procedure is divided into three phases, which are initial phase, authentication and registration phase and termination phase. This system has many advantages, including layer two independent, flexible and extensible, no need to modify current IPv6 address autoconfiguration protocols, binding update optimization, etc. Finally, the security of the protocol in this system is analyzed and proved with Extended BAN logic method, and a brief introduction of system implementation is given.

  17. Computer network access to scientific information systems for minority universities

    NASA Astrophysics Data System (ADS)

    Thomas, Valerie L.; Wakim, Nagi T.

    1993-08-01

    The evolution of computer networking technology has lead to the establishment of a massive networking infrastructure which interconnects various types of computing resources at many government, academic, and corporate institutions. A large segment of this infrastructure has been developed to facilitate information exchange and resource sharing within the scientific community. The National Aeronautics and Space Administration (NASA) supports both the development and the application of computer networks which provide its community with access to many valuable multi-disciplinary scientific information systems and on-line databases. Recognizing the need to extend the benefits of this advanced networking technology to the under-represented community, the National Space Science Data Center (NSSDC) in the Space Data and Computing Division at the Goddard Space Flight Center has developed the Minority University-Space Interdisciplinary Network (MU-SPIN) Program: a major networking and education initiative for Historically Black Colleges and Universities (HBCUs) and Minority Universities (MUs). In this paper, we will briefly explain the various components of the MU-SPIN Program while highlighting how, by providing access to scientific information systems and on-line data, it promotes a higher level of collaboration among faculty and students and NASA scientists.

  18. Alternatives for Monitoring and Limiting Network Access to Students in Network-Connected Classrooms

    ERIC Educational Resources Information Center

    Almeroth, Kevin; Zhang, Hangjin

    2013-01-01

    With the advent of laptop computers and network technology, many classrooms are now being equipped with Internet connections, either through wired connections or wireless infrastructure. Internet access provides students an additional source from which to obtain course-related information. However, constant access to the Internet can be a…

  19. NSSDC provides network access to key data via NDADS

    NASA Technical Reports Server (NTRS)

    Behnke, Jeanne; King, Joseph

    1994-01-01

    The National Space Science Data Center (NSSDC) is making a growing fraction of its most customer-desirable data electronically accessible via both the local and wide area networks. NSSDC is witnessing a great increase in its data dissemination owing to this network accessibility. To provide its customers the best data accessibility, the NSSDC makes data available from a nearline, mass storage system, the NSSDC Data Archive and Dissemination Service (NDADS). The NDADS, the initial version was made available in January 1992, is a customized system of hardware and software that provides users access to the nearline data via ANONYMOUS FTP, an e-mail interface (ARMS), and a C-based software library. In January 1992, the NDADS registered 416 requests for 1,957 files. By December of 1994, NDADS had been populated with 800 gigabytes of electronically accessible data and had registered 1458 requests for 20,887 files. In this report we describe the NDADS system, both hardware and software. Later in the report, we discuss some of the lessons that were learned as a result of operating NDADS, particularly in the area of ingest and dissemination.

  20. Epidemiologic research topics in Germany: a keyword network analysis of 2014 DGEpi conference presentations.

    PubMed

    Peter, Raphael Simon; Brehme, Torben; Völzke, Henry; Muche, Rainer; Rothenbacher, Dietrich; Büchele, Gisela

    2016-06-01

    Knowledge of epidemiologic research topics as well as trends is useful for scientific societies, researchers and funding agencies. In recent years researchers recognized the usefulness of keyword network analysis for visualizing and analyzing scientific research topics. Therefore, we applied keyword network analysis to present an overview of current epidemiologic research topics in Germany. Accepted submissions to the 9th annual congress of the German Society for Epidemiology (DGEpi) in 2014 were used as data source. Submitters had to choose one of 19 subject areas, and were ask to provide a title, structured abstract, names of authors along with their affiliations, and a list of freely selectable keywords. Keywords had been provided for 262 (82 %) submissions, 1030 keywords in total. Overall the most common keywords were: "migration" (18 times), "prevention" (15 times), followed by "children", "cohort study", "physical activity", and "secondary data analysis" (11 times each). Some keywords showed a certain concentration under one specific subject area, e.g. "migration" with 8 of 18 in social epidemiology or "breast cancer" with 4 of 7 in cancer epidemiology. While others like "physical activity" were equally distributed over multiple subject areas (cardiovascular & metabolic diseases, ageing, methods, paediatrics, prevention & health service research). This keyword network analysis demonstrated the high diversity of epidemiologic research topics with a large number of distinct keywords as presented at the annual conference of the DGEpi.

  1. Highball: A high speed, reserved-access, wide area network

    NASA Technical Reports Server (NTRS)

    Mills, David L.; Boncelet, Charles G.; Elias, John G.; Schragger, Paul A.; Jackson, Alden W.

    1990-01-01

    A network architecture called Highball and a preliminary design for a prototype, wide-area data network designed to operate at speeds of 1 Gbps and beyond are described. It is intended for applications requiring high speed burst transmissions where some latency between requesting a transmission and granting the request can be anticipated and tolerated. Examples include real-time video and disk-disk transfers, national filestore access, remote sensing, and similar applications. The network nodes include an intelligent crossbar switch, but have no buffering capabilities; thus, data must be queued at the end nodes. There are no restrictions on the network topology, link speeds, or end-end protocols. The end system, nodes, and links can operate at any speed up to the limits imposed by the physical facilities. An overview of an initial design approach is presented and is intended as a benchmark upon which a detailed design can be developed. It describes the network architecture and proposed access protocols, as well as functional descriptions of the hardware and software components that could be used in a prototype implementation. It concludes with a discussion of additional issues to be resolved in continuing stages of this project.

  2. High speed infrared optical wireless for home access networks

    NASA Astrophysics Data System (ADS)

    O'Brien, Dominic C.

    2013-12-01

    The availability of high-bandwidth internet connections to home gateways will place increasing demands on the home access network that provides connections to computers and other devices. In this paper the use of infrared optical wireless to provide connections to user appliances and terminals is discussed. The design and implementation of two demonstration systems operating at hundreds of Mbit/s and above are detailed. Future challenges are also discussed.

  3. A physical layer perspective on access network sharing

    NASA Astrophysics Data System (ADS)

    Pfeiffer, Thomas

    2015-12-01

    Unlike in copper or wireless networks, there is no sharing of resources in fiber access networks yet, other than bit stream access or cable sharing, in which the fibers of a cable are let to one or multiple operators. Sharing optical resources on a single fiber among multiple operators or different services has not yet been applied. While this would allow for a better exploitation of installed infrastructures, there are operational issues which still need to be resolved, before this sharing model can be implemented in networks. Operating multiple optical systems and services over a common fiber plant, autonomously and independently from each other, can result in mutual distortions on the physical layer. These distortions will degrade the performance of the involved systems, unless precautions are taken in the infrastructure hardware to eliminate or to reduce them to an acceptable level. Moreover, the infrastructure needs to be designed such as to support different system technologies and to ensure a guaranteed quality of the end-to-end connections. In this paper, suitable means are proposed to be introduced in fiber access infrastructures that will allow for shared utilization of the fibers while safeguarding the operational needs and business interests of the involved parties.

  4. [Healthcare access in Benin: poverty and community aid networks].

    PubMed

    Ouendo, Edgard-Marius; Makoutodé, Michel; Wilmet-Dramaix, Michèle; Paraiso, Moussiliou; Dujardin, Bruno

    2004-01-01

    The objective of this study was to evaluate the capacity of poor and non-poor households to pay for health care and to show how existing community assistance (or solidarity) networks (CAN) may compensate for this inability. Sixteen (16) study sites were randomly selected after stratification of Benin into four groups. All 1,312 households in our sample (668 poor and 664 non-poor) were interviewed, and 48 focus group were held with opinion leaders, women, healthcare workers, social workers, and persons responsible for these networks. The survey showed that only 27% of the heads of households have permanent financial access to health care and health services. This financial access is lower for the poor (9%) than for others (46%). However, the capacity of heads of households to pay reached 84% (87% for the non-poor and 81% for the poor, with P<0.01). Capacity to pay differs between strata (P<0.001) and is higher in the urban strata. For 25% of the families, intervention of the CAN made payment possible, preferentially for the poor. In 90% of cases, this community support came from the family network. Health centre management committees contributed in only 0.8% of cases. In general, help covered only a small percentage of those in need. The health policy of African countries must ensure that health care is accessible to the population, especially the poor.

  5. Shared Access Optical Networks For The Local Loop

    NASA Astrophysics Data System (ADS)

    Payne, D. B.; Stern, J. R.

    1988-09-01

    The application of single mode fibre to the local network environment opens up major opportunities for service provision via shared access networks. Previous technologies (copper pair, coaxial cable and multimode fibre) had bandwidth limitation problems that placed a severe restriction on both the level of resource sharing and the service package that could be delivered. The enormous bandwidth capability of single mode fibre can be used to provide significant resource sharing without incurring fundamental restrictions on the capacity of the services carried. The paper briefly outlines some of the activities within British Telecom on shared access systems. Early systems concepts were either based on fibre feeders to remote multiplexers for the delivery of telephony and data services to large customers or the use of advanced wavelength multiplexing techniques over passive optical networks for the transmission of wideband services to business and residential customers. Recently activity has concentrated on a passive optical network that shows good potential for the economic provision of telephony services. The structure of the network allows the later addition of broadband services via additional wavelengths without disturbing existing telephony/data customers. The basic network has a fibre feeder from the exchange to passive optical splitters housed at the Cabinet and Distribution Points (DP). Each customer receives a fibre from DP and via this a TDM multiplex broadcast from the exchange which carries the customer's traffic. The customer equipment accesses the time slots destined for the customer and delivers the data via a suitable interface to provide the services required. Customers transmit back to the exchange in a time multiplex synchronised by a ranging protocol that sets an appropriate delay in the customer equipment to avoid collisions at the optical combiners in the DPs and Cabinet. Present studies are considering a total optical split of 128 ways with a

  6. A Network Access Control Framework for 6LoWPAN Networks

    PubMed Central

    Oliveira, Luís M. L.; Rodrigues, Joel J. P. C.; de Sousa, Amaro F.; Lloret, Jaime

    2013-01-01

    Low power over wireless personal area networks (LoWPAN), in particular wireless sensor networks, represent an emerging technology with high potential to be employed in critical situations like security surveillance, battlefields, smart-grids, and in e-health applications. The support of security services in LoWPAN is considered a challenge. First, this type of networks is usually deployed in unattended environments, making them vulnerable to security attacks. Second, the constraints inherent to LoWPAN, such as scarce resources and limited battery capacity, impose a careful planning on how and where the security services should be deployed. Besides protecting the network from some well-known threats, it is important that security mechanisms be able to withstand attacks that have not been identified before. One way of reaching this goal is to control, at the network access level, which nodes can be attached to the network and to enforce their security compliance. This paper presents a network access security framework that can be used to control the nodes that have access to the network, based on administrative approval, and to enforce security compliance to the authorized nodes. PMID:23334610

  7. The Role of Inhibition in Age-related Off-Topic Verbosity: Not Access but Deletion and Restraint Functions

    PubMed Central

    Yin, Shufei; Peng, Huamao

    2016-01-01

    The speech of older adults is commonly described as verbose and off-topic, which is thought to influence their social communication. This study investigated the role of inhibition in age-related off-topic verbosity (OTV). Inhibition consists of three functions: access, deletion, and restraint. The access function is responsible for preventing irrelevant information from accessing the attention center (pre-mechanism of inhibition); The deletion function is responsible for deleting previously relevant but currently irrelevant information from working memory, and the restraint function is responsible for restraining strong but inappropriate responses (post-mechanisms of inhibition). A referential communication task was used to determine whether OTV was influenced by the pre-mechanism of inhibition. A self-involved event interview task was used to investigate the effect of the post-mechanisms of inhibition on OTV. Results showed that the OTV of the elderly participants was associated with an age-related decline in the post-mechanisms of inhibition, while the OTV exhibited by young adults was most likely due to deficits in the pre-mechanism function of inhibition. This research contributed to fill gaps in the existing knowledge about the potential relationship between specific functions of inhibition and age-related OTV. PMID:27199793

  8. Supporting Dynamic Spectrum Access in Heterogeneous LTE+ Networks

    SciTech Connect

    Luiz A. DaSilva; Ryan E. Irwin; Mike Benonis

    2012-08-01

    As early as 2014, mobile network operators’ spectral capac- ity is expected to be overwhelmed by the demand brought on by new devices and applications. With Long Term Evo- lution Advanced (LTE+) networks likely as the future one world 4G standard, network operators may need to deploy a Dynamic Spectrum Access (DSA) overlay in Heterogeneous Networks (HetNets) to extend coverage, increase spectrum efficiency, and increase the capacity of these networks. In this paper, we propose three new management frameworks for DSA in an LTE+ HetNet: Spectrum Accountability Client, Cell Spectrum Management, and Domain Spectrum Man- agement. For these spectrum management frameworks, we define protocol interfaces and operational signaling scenar- ios to support cooperative sensing, spectrum lease manage- ment, and alarm scenarios for rule adjustment. We also quan- tify, through integer programs, the benefits of using DSA in an LTE+ HetNet, that can opportunistically reuse vacant TV and GSM spectrum. Using integer programs, we consider a topology using Geographic Information System data from the Blacksburg, VA metro area to assess the realistic benefits of DSA in an LTE+ HetNet.

  9. Access to Max '91 information via computer networks

    NASA Technical Reports Server (NTRS)

    Kiplinger, Alan L.

    1989-01-01

    Various types of flare information, activity, active region reports, x ray plots and daily Campaign Action notices are now available on SPAN, and INTERNET. Although this system was developed for use by Max '91 participants during campaigns, it is updated daily and maintained at times outside of campaigns. Thus it is available for general use outside of campaigns. The Space Environment Laboratory maintains VAX and Apollo systems, both of which are on INTERNET. The VAX is also on the SPAN network as node SELVAX or 9555. Details of access to files on the VAX are given.

  10. Symmetric reconfigurable capacity assignment in a bidirectional DWDM access network.

    PubMed

    Ortega, Beatriz; Mora, José; Puerto, Gustavo; Capmany, José

    2007-12-10

    This paper presents a novel architecture for DWDM bidirectional access networks providing symmetric dynamic capacity allocation for both downlink and uplink signals. A foldback arrayed waveguide grating incorporating an optical switch enables the experimental demonstration of flexible assignment of multiservice capacity. Different analog and digital services, such as CATV, 10 GHz-tone, 155Mb/s PRBS and UMTS signals have been transmitted in order to successfully test the system performance under different scenarios of total capacity distribution from the Central Station to different Base Stations with two reconfigurable extra channels for each down and upstream direction. PMID:19550967

  11. Amplified CWDM-based Next Generation Broadband Access Networks

    NASA Astrophysics Data System (ADS)

    Peiris, Sasanthi Chamarika

    The explosive growth of both fixed and mobile data-centric traffic along with the inevitable trend towards all-IP/Ethernet transport protocols and packet switched networks will ultimately lead to an all-packet-based converged fixed-mobile optical transport network from the core all the way out to the access network. To address the increasing capacity and speed requirements in the access networks, Wavelength-Division Multiplexed (WDM) and/or Coarse WDM (CWDM)-based Passive Optical Networks (PONs) are expected to emerge as the next-generation optical access infrastructures. However, due to several techno-economic hurdles, CWDM-PONs are still considered an expensive solution and have not yet made any significant inroads into the current access area. One of the key technology hurdles is the scalability of the CWDM-based PONs. Passive component optical insertion losses limit the reach of the network or the number of served optical network units (ONUs). In the recent years, optical amplified CWDM approaches have emerged and new designs of optical amplifiers have been proposed and demonstrated. The critical design parameter for these amplifiers is the very wide optical amplification bandwidth (e.g., 340 nm combined for both directions). The objective of this PhD dissertation work is first to engineer ring and tree-ring based PON architectures that can achieve longer unamplified PON reach and/or provide service to a greater number of ONUs and customers. Secondly is to develop new novel optical amplifier schemes to further address the scalability limitation of the CWDM-based PONs. Specifically, this work proposes and develops novel ultra wide-band hybrid Raman-Optical parametric amplifier (HROPA) schemes that operate over nearly the entire specified CWDM band to provide 340 nm bidirectional optical gain bandwidth over the amplified PON's downstream and upstream CWDM wavelength bands (about 170 nm in each direction). The performance of the proposed HROPA schemes is assessed

  12. New broadband access technology: Ethernet passive optical network (EPON)

    NASA Astrophysics Data System (ADS)

    Zhu, Lili; Fan, Xiliang; He, Yan

    2004-04-01

    A newly broadband access technology comes into being with the combination of IP and access technique, which is considered as EPON (Ethernet passive optical network). EPON system resolves the limitation of point-to-point, instead uses the topology architecture of point-to-multipoint. It extends the fiber cable to the last mile, so we can get the end-to-end network system with high efficiency, well expansibility and low maintenance cost. There are many key techniques and problems in EPON system, for example, CDR (Clock and data recovery), RTT (Round-Trip Time), DBA (Dynamic Bandwidth Allocation) and ULSLE (Upper-Layer Shared LAN Emulation). The essential character of MPCP (Multi-Point Control Protocol) used in EPON is to schedule the transmission of the upstream data packets, and to avoid data collision. A central counter is applied to synchronize the upstream data through a time-stamp flag. A REPORT control frame is transmitted, which give the length of the different priority queues. On receiving this control frame, central office device modifies the bandwidth allocation in the grant table. The function relating to the ULSLE protocol is similar with IEEE802.1D Bridge, and also includes point-to-multipoint, therefore so many problems are resolved, such as the frame reflection, the communication among different ONUs.

  13. A study of multiple access schemes in satellite control network

    NASA Astrophysics Data System (ADS)

    Mo, Zijian; Wang, Zhonghai; Xiang, Xingyu; Wang, Gang; Chen, Genshe; Nguyen, Tien; Pham, Khanh; Blasch, Erik

    2016-05-01

    Satellite Control Networks (SCN) have provided launch control for space lift vehicles; tracking, telemetry and commanding (TTC) for on-orbit satellites; and, test support for space experiments since the 1960s. Currently, SCNs encounter a new challenge: how to maintain the high reliability of services when sharing the spectrum with emerging commercial services. To achieve this goal, the capability of multiple satellites reception is deserved as an update/modernization of SCN in the future. In this paper, we conducts an investigation of multiple access techniques in SCN scenario, e.g., frequency division multiple access (FDMA) and coded division multiple access (CDMA). First, we introduce two upgrade options of SCN based on FDMA and CDMA techniques. Correspondingly, we also provide their performance analysis, especially the system improvement in spectrum efficiency and interference mitigation. Finally, to determine the optimum upgrade option, this work uses CRISP, i.e., Cost, Risk, Installation, Supportability and Performance, as the baseline approach for a comprehensive trade study of these two options. Extensive numerical and simulation results are presented to illustrate the theoretical development.

  14. 47 CFR 51.307 - Duty to provide access on an unbundled basis to network elements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... network elements. 51.307 Section 51.307 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED... Carriers § 51.307 Duty to provide access on an unbundled basis to network elements. (a) An incumbent LEC... service, nondiscriminatory access to network elements on an unbundled basis at any technically...

  15. 47 CFR 51.311 - Nondiscriminatory access to unbundled network elements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... elements. 51.311 Section 51.311 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON... § 51.311 Nondiscriminatory access to unbundled network elements. (a) The quality of an unbundled network element, as well as the quality of the access to the unbundled network element, that an...

  16. 47 CFR 51.311 - Nondiscriminatory access to unbundled network elements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... elements. 51.311 Section 51.311 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON... § 51.311 Nondiscriminatory access to unbundled network elements. (a) The quality of an unbundled network element, as well as the quality of the access to the unbundled network element, that an...

  17. 47 CFR 51.311 - Nondiscriminatory access to unbundled network elements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... elements. 51.311 Section 51.311 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON... § 51.311 Nondiscriminatory access to unbundled network elements. (a) The quality of an unbundled network element, as well as the quality of the access to the unbundled network element, that an...

  18. 47 CFR 51.311 - Nondiscriminatory access to unbundled network elements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... elements. 51.311 Section 51.311 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON... § 51.311 Nondiscriminatory access to unbundled network elements. (a) The quality of an unbundled network element, as well as the quality of the access to the unbundled network element, that an...

  19. 47 CFR 51.311 - Nondiscriminatory access to unbundled network elements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... elements. 51.311 Section 51.311 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON... § 51.311 Nondiscriminatory access to unbundled network elements. (a) The quality of an unbundled network element, as well as the quality of the access to the unbundled network element, that an...

  20. 47 CFR 51.307 - Duty to provide access on an unbundled basis to network elements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... network elements. 51.307 Section 51.307 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED... Carriers § 51.307 Duty to provide access on an unbundled basis to network elements. (a) An incumbent LEC... service, nondiscriminatory access to network elements on an unbundled basis at any technically...

  1. Software Defined Networking for Next Generation Converged Metro-Access Networks

    NASA Astrophysics Data System (ADS)

    Ruffini, M.; Slyne, F.; Bluemm, C.; Kitsuwan, N.; McGettrick, S.

    2015-12-01

    While the concept of Software Defined Networking (SDN) has seen a rapid deployment within the data center community, its adoption in telecommunications network has progressed slowly, although the concept has been swiftly adopted by all major telecoms vendors. This paper presents a control plane architecture for SDN-driven converged metro-access networks, developed through the DISCUS European FP7 project. The SDN-based controller architecture was developed in a testbed implementation targeting two main scenarios: fast feeder fiber protection over dual-homed Passive Optical Networks (PONs) and dynamic service provisioning over a multi-wavelength PON. Implementation details and results of the experiment carried out over the second scenario are reported in the paper, showing the potential of SDN in providing assured on-demand services to end-users.

  2. Modelling high data rate communication network access protocol

    NASA Technical Reports Server (NTRS)

    Khanna, S.; Foudriat, E. C.; Paterra, Frank; Maly, Kurt J.; Overstreet, C. Michael

    1990-01-01

    Modeling of high data rate communication systems is different from the low data rate systems. Three simulations were built during the development phase of Carrier Sensed Multiple Access/Ring Network (CSMA/RN) modeling. The first was a model using SIMCRIPT based upon the determination and processing of each event at each node. The second simulation was developed in C based upon isolating the distinct object that can be identified as the ring, the message, the node, and the set of critical events. The third model further identified the basic network functionality by creating a single object, the node which includes the set of critical events which occur at the node. The ring structure is implicit in the node structure. This model was also built in C. Each model is discussed and their features compared. It should be stated that the language used was mainly selected by the model developer because of his past familiarity. Further the models were not built with the intent to compare either structure or language but because the complexity of the problem and initial results contained obvious errors, so alternative models were built to isolate, determine, and correct programming and modeling errors. The CSMA/RN protocol is discussed in sufficient detail to understand modeling complexities. Each model is described along with its features and problems. The models are compared and concluding observations and remarks are presented.

  3. Texas coastal ocean observation network: data access and archive software

    NASA Astrophysics Data System (ADS)

    Jeffress, Gary A.; Duff, J. Scott

    2011-06-01

    The Conrad Blucher Institute for Surveying and Science (CBI) at Texas A&M University-Corpus Christi operates the Texas Coastal Ocean Observation Network (TCOON.) The network collects near real-time physical oceanographic data at 31 coastal stations along the Texas coast. The data includes water level, wind speed & direction, barometric pressure, water temperature, and air temperature from stations placed in bays and estuaries along the Texas coast. TCOON provides this critical data to many users, including those in the commercial shipping industry, marine construction, legal water-land boundaries, recreational boaters, and those responsible for marine safety and emergency evacuation in the event of a hurricane. Data sets are available in near real time via the Internet and some sets are accessible via voice over the telephone. All data collected since 1991 is available online along with data search tools. TCOON sponsors and developers believe that the more users and uses the system supports, the more valuable the data becomes. The highest scientific standards are used in collection the data as the data often ends up in litigation in the courts. Database software and the online tools used for data downloads are also open source.

  4. 47 CFR 51.318 - Eligibility criteria for access to certain unbundled network elements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... unbundled network elements. 51.318 Section 51.318 Telecommunication FEDERAL COMMUNICATIONS COMMISSION... Exchange Carriers § 51.318 Eligibility criteria for access to certain unbundled network elements. (a... network elements and combinations of unbundled network elements without regard to whether the...

  5. 47 CFR 51.318 - Eligibility criteria for access to certain unbundled network elements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... unbundled network elements. 51.318 Section 51.318 Telecommunication FEDERAL COMMUNICATIONS COMMISSION... Exchange Carriers § 51.318 Eligibility criteria for access to certain unbundled network elements. (a... network elements and combinations of unbundled network elements without regard to whether the...

  6. Improved small satellite access of the space network

    NASA Technical Reports Server (NTRS)

    Horan, Stephen; Osborne, William P.; Minnix, Timothy

    1994-01-01

    This report contains the results of a study performed under the sponsorship of the National Aeronautics and Space Administration (NASA) made as a grant to the Center for Space Telemetering and Telecommunication Systems at New Mexico State University. The purpose of this phase of the grant is to increase user access to the Space Network (SN) run by NASA for supplying space-to-ground communications for satellites and associated control centers. The identified need is to bring more users into the community of those accessing the SN, especially those in the small satellite class of users. The initial phase of the study concerned the potential for modifications to the standard transponder used in the SN. The results of that investigation are summarized in Section 4. As the hardware modifications were being investigated, a second option was developed, namely to consider changes to the operational mode for the small satellites. This operational concept was to use a single, fixed-pointing antenna in a spin-stabilized satellite and let the antenna pattern sweep past the Tracking and Data Relay Satellites (TDRS) in the SN. The question to be answered by this phase of the study was twofold: could enough contact time per day be made available using this simple operating mode and could the data rate be high enough to allow for sufficient data throughput to satisfy the user community using existing components. Section 2 outlines the methodology and simulation results to answer these questions. Section 3 contains a summary of an operational simulation of a simple satellite payload using these contact scenarios. The simulation is not all inclusive but shows how a payload simulation could be configured to utilize variable contact times. The answer to both of the questions desired to be answered is affirmative. By carefully choosing the correct system transmission power and antenna pattern, the system will allow support to the 50th percentile of expected systems. It is recommended

  7. Regional Webgis User Access Patterns Based on a Weighted Bipartite Network

    NASA Astrophysics Data System (ADS)

    Li, R.; Shen, Y.; Huang, W.; Wu, H.

    2015-07-01

    With the rapid development of geographic information services, Web Geographic Information Systems (WebGIS) have become an indispensable part of everyday life; correspondingly, map search engines have become extremely popular with users and WebGIS sites receive a massive volume of requests for access. These WebGIS users and the content accessed have regional characteristics; to understand regional patterns, we mined regional WebGIS user access patterns based on a weighted bipartite network. We first established a weighted bipartite network model for regional user access to a WebGIS. Then, based on the massive user WebGIS access logs, we clustered geographic information accessed and thereby identified hot access areas. Finally we quantitatively analyzed the access interests of regional users and the visitation volume characteristics of regional user access to these hot access areas in terms of user access permeability, user usage rate, and user access viscosity. Our research results show that regional user access to WebGIS is spatially aggregated, and the hot access areas that regional users accessed are associated with specific periods of time. Most regional user contact with hot accessed areas is variable and intermittent but for some users, their access to certain areas is continuous as it is associated with ongoing or recurrent objectives. The weighted bipartite network model for regional user WebGIS access provides a valid analysis method for studying user behaviour in WebGIS and the proposed access pattern exhibits access interest of regional user is spatiotemporal aggregated and presents a heavy-tailed distribution. Understanding user access patterns is good for WebGIS providers and supports better operational decision-making, and helpful for developers when optimizing WebGIS system architecture and deployment, so as to improve the user experience and to expand the popularity of WebGIS.

  8. Social Capital for College: Network Composition and Access to Selective Institutions among Urban High School Students

    ERIC Educational Resources Information Center

    Hill, Lori Diane; Bregman, Allyson; Andrade, Fernando

    2015-01-01

    This study examines the relationship between networks that provide high school students with "social capital for college" (SCFC) and their access to selective institutions. It also explores the link between racial disparities in access to selective colleges and the composition of students' SCFC networks. Findings indicate that while…

  9. US-Finland Planning Visit: Cooperative Research and Education Activities in Integrated Access Networks

    NASA Astrophysics Data System (ADS)

    Maclin, Arlene; University of Arizona-CIAN Collaboration; Aalto University in Finland Collaboration

    2011-03-01

    This planning grant visit sponsored by the NSF Office of International Science and Engineering occurred from October 3-10, 2010. The Dean of the School of Computer, Mathematical and Natural Sciences from Morgan State University (MSU), the PI and a faculty member from engineering at MSU along with a faculty member from the University of Arizona and two advanced level graduate students from the NSF-funded Center for Integrated Access Networks participated in this visit. The topic of novel low dimensional nano-materials was determined to be one possible area for future collaboration. As a result of this visit, a Materials World Network proposal has been submitted to the NSF involving MSU and CIAN in the US and Aalto University in Finland. A companion proposal on novel low dimensional nano- materials has also been submitted to the Academy of Finland. Another anticipated outcome of this collaboration of MSU with Aalto University and CIAN expands the outreach and diversity component to MSU, an institution serving largely an underrepresented minority student. Sponsor for this work was NSF # 1042309.

  10. Experimental realization of an entanglement access network and secure multi-party computation.

    PubMed

    Chang, X-Y; Deng, D-L; Yuan, X-X; Hou, P-Y; Huang, Y-Y; Duan, L-M

    2016-01-01

    To construct a quantum network with many end users, it is critical to have a cost-efficient way to distribute entanglement over different network ends. We demonstrate an entanglement access network, where the expensive resource, the entangled photon source at the telecom wavelength and the core communication channel, is shared by many end users. Using this cost-efficient entanglement access network, we report experimental demonstration of a secure multiparty computation protocol, the privacy-preserving secure sum problem, based on the network quantum cryptography.

  11. Experimental realization of an entanglement access network and secure multi-party computation.

    PubMed

    Chang, X-Y; Deng, D-L; Yuan, X-X; Hou, P-Y; Huang, Y-Y; Duan, L-M

    2016-01-01

    To construct a quantum network with many end users, it is critical to have a cost-efficient way to distribute entanglement over different network ends. We demonstrate an entanglement access network, where the expensive resource, the entangled photon source at the telecom wavelength and the core communication channel, is shared by many end users. Using this cost-efficient entanglement access network, we report experimental demonstration of a secure multiparty computation protocol, the privacy-preserving secure sum problem, based on the network quantum cryptography. PMID:27404561

  12. Experimental realization of an entanglement access network and secure multi-party computation

    PubMed Central

    Chang, X.-Y.; Deng, D.-L.; Yuan, X.-X.; Hou, P.-Y.; Huang, Y.-Y.; Duan, L.-M.

    2016-01-01

    To construct a quantum network with many end users, it is critical to have a cost-efficient way to distribute entanglement over different network ends. We demonstrate an entanglement access network, where the expensive resource, the entangled photon source at the telecom wavelength and the core communication channel, is shared by many end users. Using this cost-efficient entanglement access network, we report experimental demonstration of a secure multiparty computation protocol, the privacy-preserving secure sum problem, based on the network quantum cryptography. PMID:27404561

  13. Experimental realization of an entanglement access network and secure multi-party computation

    NASA Astrophysics Data System (ADS)

    Chang, X.-Y.; Deng, D.-L.; Yuan, X.-X.; Hou, P.-Y.; Huang, Y.-Y.; Duan, L.-M.

    2016-07-01

    To construct a quantum network with many end users, it is critical to have a cost-efficient way to distribute entanglement over different network ends. We demonstrate an entanglement access network, where the expensive resource, the entangled photon source at the telecom wavelength and the core communication channel, is shared by many end users. Using this cost-efficient entanglement access network, we report experimental demonstration of a secure multiparty computation protocol, the privacy-preserving secure sum problem, based on the network quantum cryptography.

  14. The Role of Social Network Locations in the College Access Mentoring of Urban Youth

    ERIC Educational Resources Information Center

    Ahn, June

    2010-01-01

    This study uses social network analysis to describe the social network of college mentors in a college access program. Urban students in the program are paired with college mentors-students, professors, and other institutional agents-to help improve their college going process. The study analyzes the social networks within which the mentors are…

  15. Implementation of levels of services on broadband networks with cable modem access

    NASA Astrophysics Data System (ADS)

    Campos, Luis A.; Yu, Che-Fn

    1997-10-01

    Residential broadband access networks using technologies such as ADSL and cable modems have enabled the provisioning of emerging Internet applications such as Internet telephony, video conferencing and interactive games. These applications have specific end-to-end performance requirements from the network in order to have an acceptable performance. Currently the Internet is a best effort network which doesn't provide levels of service. There are many elements of an end-to-end network which are currently suitable to provide quality-of- service guaranties such as ATM links. Nevertheless, only with recent deployments of broadband access technologies and the introduction of Internet protocols such as RSVP, providing levels of service becomes feasible without the use expensive links to the customer site. This paper examines several network implementation options for introducing levels of service using cable modem access. Limitations imposed by the applications on the network as well as the contribution of the different network elements to level of service parameters such as end-to-end delay, throughput and jitter are examined. Concentration network architectures as well as proposed backbone configuration options for end-to-end level of service provisioning are presented. At the access network, provisioning of level of service using bandwidth control through packet throttling and through access network design providing excess bandwidth to customers are presented. HFC protocol dependent means to provide level of services including reservation and ATM based protocols are examined as well.

  16. An effective access control approach to support mobility in IPv6 networks

    NASA Astrophysics Data System (ADS)

    Peng, Xue-hai; Lin, Chuang

    2005-11-01

    Access control is an important method to improve network security and prevent protected resources from being used by some nodes without authority. Moreover, mobility is an important trend of internet. In this paper, based on the architecture of hierarchical mobile IPv6, we proposed an effective access control approach to support mobility in IPv6 networks, which can ensure the operation of access control when a mobile node roams in these domains with different polices, with decreased delay of access negotiation and cost of delivering messages.

  17. Position Estimation of Access Points in 802.11 Wireless Networks

    SciTech Connect

    Kent, C A; Dowla, F U; Atwal, P K; Lennon, W J

    2003-12-05

    We developed a technique to locate wireless network nodes using multiple time-of-flight range measurements in a position estimate. When used with communication methods that allow propagation through walls, such as Ultra-Wideband and 802.11, we can locate network nodes in buildings and in caves where GPS is unavailable. This paper details the implementation on an 802.11a network where we demonstrated the ability to locate a network access point to within 20 feet.

  18. Guaranteed Access to Campus Network Resources: Policies and Issues.

    ERIC Educational Resources Information Center

    Hassler, Ardoth A.

    1998-01-01

    Reports on a options and issues discussion at a December 1997 Orlando (Florida) meeting of CAUSE97 on providing access to campus technology resources. Options discussed included departmentally and/or university-owned modems, third-party provider contracts, and using wireless access. Issues included providing authentication, assuring network…

  19. Design mobile satellite system architecture as an integral part of the cellular access digital network

    NASA Technical Reports Server (NTRS)

    Chien, E. S. K.; Marinho, J. A.; Russell, J. E., Sr.

    1988-01-01

    The Cellular Access Digital Network (CADN) is the access vehicle through which cellular technology is brought into the mainstream of the evolving integrated telecommunications network. Beyond the integrated end-to-end digital access and per call network services provisioning of the Integrated Services Digital Network (ISDN), the CADN engenders the added capability of mobility freedom via wireless access. One key element of the CADN network architecture is the standard user to network interface that is independent of RF transmission technology. Since the Mobile Satellite System (MSS) is envisioned to not only complement but also enhance the capabilities of the terrestrial cellular telecommunications network, compatibility and interoperability between terrestrial cellular and mobile satellite systems are vitally important to provide an integrated moving telecommunications network of the future. From a network standpoint, there exist very strong commonalities between the terrestrial cellular system and the mobile satellite system. Therefore, the MSS architecture should be designed as an integral part of the CADN. This paper describes the concept of the CADN, the functional architecture of the MSS, and the user-network interface signaling protocols.

  20. The Design of Passive Optical Networking+Ethernet over Coaxial Cable Access Networking and Video-on-Demand Services Carrying

    NASA Astrophysics Data System (ADS)

    Ji, Wei

    2013-07-01

    Video on demand is a very attractive service used for entertainment, education, and other purposes. The design of passive optical networking+Ethernet over coaxial cable accessing and a home gateway system is proposed. The network integrates the passive optical networking and Ethernet over coaxial cable to provide high dedicated bandwidth for the metropolitan video-on-demand services. Using digital video broadcasting, IP television protocol, unicasting, and broadcasting mechanisms maximizes the system throughput. The home gateway finishes radio frequency signal receiving and provides three kinds of interfaces for high-definition video, voice, and data, which achieves triple-play and wire/wireless access synchronously.

  1. Topical application of alpha-tocopherol modulates the antioxidant network and diminishes ultraviolet-induced oxidative damage in murine skin.

    PubMed

    Lopez-Torres, M; Thiele, J J; Shindo, Y; Han, D; Packer, L

    1998-02-01

    The aim of this study was to investigate the effects of topical alpha-tocopherol application on epidermal and dermal antioxidants and its ability to prevent ultraviolet (UV)-induced oxidative damage. Hairless mice received topical applications of alpha-tocopherol 24 h before a single, acute UV irradiation (10 x minimal erythemal dose). The four major antioxidant enzymes (catalase, superoxide dismutase, glutathione reductase and glutathione peroxidase), hydrophilic and lipophilic antioxidants, and lipid hydroperoxides, markers of oxidative damage, were assayed in both epidermis and dermis of hairless mice. Topical alpha-tocopherol treatment increased dermal superoxide dismutase activity by 30% (P < 0.01) and protected epidermal glutathione peroxidase and superoxide dismutase from depletion after UV irradiation. Total and reduced glutathione levels in the epidermis increased by 50% after the topical treatment (P < 0.05), as did dermal ascorbate levels (by 40%: P < 0.01). The topical treatment increased alpha-tocopherol levels both in the epidermis (62-fold) and the dermis (22-fold: P < 0.001 in each layer). Furthermore, alpha-tocopherol treatment significantly reduced the formation of epidermal lipid hydroperoxides after UV irradiation (P < 0.05). These results demonstrate that topical administration of alpha-tocopherol protects cutaneous tissues against oxidative damage induced by UV irradiation in vivo, and suggest that the underlying mechanism of this effect involves the up-regulation of a network of enzymatic and non-enzymatic antioxidants.

  2. Simulation and measurement of optical access network with different types of optical-fiber amplifiers

    NASA Astrophysics Data System (ADS)

    Latal, Jan; Vogl, Jan; Koudelka, Petr; Vitasek, Jan; Siska, Petr; Liner, Andrej; Papes, Martin; Vasinek, Vladimir

    2012-01-01

    The optical access networks are nowadays swiftly developing in the telecommunications field. These networks can provide higher data transfer rates, and have great potential to the future in terms of transmission possibilities. Many local internet providers responded to these facts and began gradually installing optical access networks into their originally built networks, mostly based on wireless communication. This allowed enlargement of possibilities for end-users in terms of high data rates and also new services such as Triple play, IPTV (Internet Protocol television) etc. However, with this expansion and building-up is also related the potential of reach in case of these networks. Big cities, such as Prague, Brno, Ostrava or Olomouc cannot be simply covered, because of their sizes and also because of their internal regulations given by various organizations in each city. Standard logical and also physical reach of EPON (IEEE 802.3ah - Ethernet Passive Optical Network) optical access network is about 20 km. However, for networks based on Wavelength Division Multiplex the reach can be up to 80 km, if the optical-fiber amplifier is inserted into the network. This article deals with simulation of different types of amplifiers for WDM-PON (Wavelength Division Multiplexing-Passive Optical Network) network in software application Optiwave OptiSystem and than are the values from the application and from real measurement compared.

  3. An Ounce of Prevention: Technologists Use Network-Access Control to Protect System Resources, Students

    ERIC Educational Resources Information Center

    Bolch, Matt

    2009-01-01

    Whether for an entire district, a single campus, or one classroom, allowing authorized access to a computer network can be fraught with challenges. The login process should be fairly seamless to approved users, giving them speedy access to approved Web sites, databases, and other sources of information. It also should be tough on unauthorized…

  4. The Cybermobile: A Gateway for Public Access to Network-Based Information.

    ERIC Educational Resources Information Center

    Drumm, John E.; Groom, Frank M.

    1997-01-01

    Though the bookmobile has fallen on hard times, the cybermobile, a technology platform combining personal computing, CD-ROMs, fiber network, and wireless access to the Internet, may be the next step in mobile library services. Discusses standard vehicle, computer hardware, software, wireless access, and alliances with users, vendors, and community…

  5. The Changing Role of Community Networks in Providing Citizen Access to the Internet.

    ERIC Educational Resources Information Center

    Keenan, Thomas P.; Trotter, David Mitchell

    1999-01-01

    Examines the changing role of community network associations or freenets in providing Internet access by examining the case of the Calgary Community Network Association (CCNA) in Alberta, Canada. Discusses the withdrawal of states from the telecommunications field, priorities of the Canadian government, and the role of the private sector.…

  6. 47 CFR 51.318 - Eligibility criteria for access to certain unbundled network elements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... unbundled network elements. 51.318 Section 51.318 Telecommunication FEDERAL COMMUNICATIONS COMMISSION... Exchange Carriers § 51.318 Eligibility criteria for access to certain unbundled network elements. (a... telecommunications carrier has received state certification to provide local voice service in the area being...

  7. Optical Multiple Access Network (OMAN) for advanced processing satellite applications

    NASA Technical Reports Server (NTRS)

    Mendez, Antonio J.; Gagliardi, Robert M.; Park, Eugene; Ivancic, William D.; Sherman, Bradley D.

    1991-01-01

    An OMAN breadboard for exploring advanced processing satellite circuit switch applications is introduced. Network architecture, hardware trade offs, and multiple user interference issues are presented. The breadboard test set up and experimental results are discussed.

  8. EAP-Kerberos: A Low Latency EAP Authentication Method for Faster Handoffs in Wireless Access Networks

    NASA Astrophysics Data System (ADS)

    Zrelli, Saber; Okabe, Nobuo; Shinoda, Yoichi

    The wireless medium is a key technology for enabling ubiquitous and continuous network connectivity. It is becoming more and more important in our daily life especially with the increasing adoption of networking technologies in many fields such as medical care and transportation systems. Although most wireless technologies nowadays provide satisfying bandwidth and higher speeds, several of these technologies still lack improvements with regard to handoff performance. In this paper, we focus on wireless network technologies that rely on the Extensible Authentication Protocol for mutual authentication between the station and the access network. Such technologies include local area wireless networks (IEEE 802.11) as well as broadband wireless networks (IEEE 802.16). We present a new EAP authentication method based on a three party authentication scheme, namely Kerberos, that considerably shortens handoff delays. Compared to other methods, the proposed method has the advantage of not requiring any changes on the access points, making it readily deployable at reasonable costs.

  9. A study on new nursing information accessibility mechanism using the digital broadcasting network.

    PubMed

    Oh, Jina

    2006-01-01

    There have been efforts to add an interoperability function to TV systems. The digital technology has changed all our lifestyles. Now TV systems do indeed have interoperability functions. However, this means more than interoperable TV. It announces the birth of a digital broadcasting network (one-source and many-destination digital communication mechanism)--the new digital communication network as a broadcasting style. As a viewpoint of nursing informatics, this mechanism provides a new accessibility mechanism to structured and interoperable data. This paper introduces the technology and the basic scenarios on the data accessibility mechanism using the digital broadcasting network.

  10. A study on new nursing information accessibility mechanism using the digital broadcasting network.

    PubMed

    Oh, Jina

    2006-01-01

    There have been efforts to add an interoperability function to TV systems. The digital technology has changed all our lifestyles. Now TV systems do indeed have interoperability functions. However, this means more than interoperable TV. It announces the birth of a digital broadcasting network (one-source and many-destination digital communication mechanism)--the new digital communication network as a broadcasting style. As a viewpoint of nursing informatics, this mechanism provides a new accessibility mechanism to structured and interoperable data. This paper introduces the technology and the basic scenarios on the data accessibility mechanism using the digital broadcasting network. PMID:17102340

  11. Public Access; Public Interest. The Network Project. Notebook Number 11.

    ERIC Educational Resources Information Center

    Columbia Univ., New York, NY. Network Project.

    The transcript of a panel discussion and an essay on public access to and control of society's information resources are presented. It is contended that the electronic Media--including radio, television, and communication satellites--are controlled by a select group of individuals and corporations and that they are not meeting the public interest.…

  12. Next generation communications satellites: Multiple access and network studies

    NASA Technical Reports Server (NTRS)

    Stern, T. E.; Schwartz, M.; Meadows, H. E.; Ahmadi, H. K.; Gadre, J. G.; Gopal, I. S.; Matsmo, K.

    1980-01-01

    Following an overview of issues involved in the choice of promising system architectures for efficient communication with multiple small inexpensive Earth stations serving hetergeneous user populations, performance evaluation via analysis and simulation for six SS/TDMA (satellite-switched/time-division multiple access) system architectures is discussed. These configurations are chosen to exemplify the essential alternatives available in system design. Although the performance evaluation analyses are of fairly general applicability, whenever possible they are considered in the context of NASA's 30/20 GHz studies. Packet switched systems are considered, with the assumption that only a part of transponder capacit is devoted to packets, the integration of circuit and packet switched traffic being reserved for further study. Three types of station access are distinguished: fixed (FA), demand (DA), and random access (RA). Similarly, switching in the satellite can be assigned on a fixed (FS) or demand (DS) basis, or replaced by a buffered store-and-forward system (SF) onboard the satellite. Since not all access/switching combinations are practical, six systems are analyzed in detail: three FS SYSTEMS, FA/FS, DA/ES, RA/FS; one DS system, DA/DS; and two SF systems, FA/SF, DA/SF. Results are presented primarily in terms of delay-throughput characteristics.

  13. Homeless Families' Education Networks: An Examination of Access and Mobilization

    ERIC Educational Resources Information Center

    Miller, Peter M.

    2011-01-01

    Purpose: This study sought deeper understanding of how sheltered families accessed and mobilized educationally related relationships and resources during periods of homelessness. Such work is posited to be especially relevant considering that there is a growing crisis of family homelessness in the United States and school- and community-based…

  14. Adaptive coded spreading OFDM signal for dynamic-λ optical access network

    NASA Astrophysics Data System (ADS)

    Liu, Bo; Zhang, Lijia; Xin, Xiangjun

    2015-12-01

    This paper proposes and experimentally demonstrates a novel adaptive coded spreading (ACS) orthogonal frequency division multiplexing (OFDM) signal for dynamic distributed optical ring-based access network. The wavelength can be assigned to different remote nodes (RNs) according to the traffic demand of optical network unit (ONU). The ACS can provide dynamic spreading gain to different signals according to the split ratio or transmission length, which offers flexible power budget for the network. A 10×13.12 Gb/s OFDM access with ACS is successfully demonstrated over two RNs and 120 km transmission in the experiment. The demonstrated method may be viewed as one promising for future optical metro access network.

  15. Assessment methodology of protection schemes for next generation optical access networks

    NASA Astrophysics Data System (ADS)

    Mas Machuca, Carmen; Wosinska, Lena; Chen, Jiajia

    2015-12-01

    Optical access networks are evolving towards next generation solutions offering much higher bandwidth per end point. Moreover, the uninterrupted access to the network services is becoming crucial and therefore operators are now considering protecting their access networks. However, the cost factor is still very important due to the relatively low cost sharing in access segment. For this purpose, this paper proposes an assessment methodology that can be used to compare different protection schemes and help to identify the suitable solution for a given scenario. The assessment criteria includes some reliability measures such as Failure Impact Factor (FIF) and connection availability, as well as cost parameters such as the investment required in greenfield and brownfield scenarios and the increase in power consumption compared to the unprotected network. The proposed criteria have been used to compare 7 representative protection schemes shown in literature, which differ mainly in the number of protected network elements and the technology used for protection (fiber, wireless, etc.). The considered protection schemes have been applied to a hybrid wavelength division multiplexing/time division multiplexing Passive Optical Network (Hybrid PON) architecture in an urban area. It has been shown that it is difficult to identify the absolute best scheme with respect to all the considered criteria. However, depending on the requirements from the operator regarding the targeted reliability performance in the network, an appropriate protection scheme can be recommended for either a greenfield or a brownfield scenario.

  16. A metro-access integrated network with all-optical virtual private network function using DPSK/ASK modulation format

    NASA Astrophysics Data System (ADS)

    Tian, Yue; Leng, Lufeng; Su, Yikai

    2008-11-01

    All-optical virtual private network (VPN), which offers dedicated optical channels to connect users within a VPN group, is considered a promising approach to efficient internetworking with low latency and enhanced security implemented in the physical layer. On the other hand, time-division multiplexed (TDM) / wavelength-division multiplexed (WDM) network architecture based on a feeder-ring with access-tree topology, is considered a pragmatic migration scenario from current TDM-PONs to future WDM-PONs and a potential convergence scheme for access and metropolitan networks, due to its efficiently shared hardware and bandwidth resources. All-optical VPN internetworking in such a metro-access integrated structure is expected to cover a wider service area and therefore is highly desirable. In this paper, we present a TDM/WDM metro-access integrated network supporting all-optical VPN internetworking among ONUs in different sub- PONs based on orthogonal differential-phase-shift keying (DPSK) / amplitude-shift keying (ASK) modulation format. In each ONU, no laser but a single Mach-Zehnder modulator (MZM) is needed for the upstream and VPN signal generation, which is cost-effective. Experiments and simulations are performed to verify its feasibility as a potential solution to the future access service.

  17. The ARAC client system: network-based access to ARAC

    SciTech Connect

    Leach, M J; Sumikawa, D; Webster, C

    1999-07-12

    The ARAC Client System allows users (such as emergency managers and first responders) with commonly available desktop and laptop computers to utilize the central ARAC system over the Internet or any other communications link using Internet protocols. Providing cost-effective fast access to the central ARAC system greatly expands the availability of the ARAC capability. The ARAC Client system consists of (1) local client applications running on the remote user's computer, and (2) ''site servers'' that provide secure access to selected central ARAC system capabilities and run on a scalable number of dedicated workstations residing at the central facility. The remote client applications allow users to describe a real or potential them-bio event, electronically sends this information to the central ARAC system which performs model calculations, and quickly receive and visualize the resulting graphical products. The site servers will support simultaneous access to ARAC capabilities by multiple users. The ARAC Client system is based on object-oriented client/server and distributed computing technologies using CORBA and Java, and consists of a large number of interacting components.

  18. A Comparative Study of Multiplexing Schemes for Next Generation Optical Access Networks

    NASA Astrophysics Data System (ADS)

    Imtiaz, Waqas A.; Khan, Yousaf; Shah, Pir Mehar Ali; Zeeshan, M.

    2014-09-01

    Passive optical network (PON) is a high bandwidth, economical solution which can provide the necessary bandwidth to end-users. Wavelength division multiplexed passive optical networks (WDM PONs) and time division multiplexed passive optical networks (TDM PONs) are considered as an evolutionary step for next-generation optical access (NGOA) networks. However they fail to provide highest transmission capacity, efficient bandwidth access, and robust dispersion tolerance. Thus future PONs are considered on simpler, efficient and potentially scalable, optical code division multiplexed (OCDM) PONs. This paper compares the performance of existing PONs with OCDM PON to determine a suitable scheme for NGOA networks. Two system parameter are used in this paper: fiber length, and bit rate. Performance analysis using Optisystem shows that; for a sufficient system performance parameters i.e. bit error rate (BER) ≤ 10-9, and maximum quality factor (Q) ≥ 6, OCDMA PON efficiently performs upto 50 km with 10 Gbit/s per ONU.

  19. Comparative effectiveness of topical drugs in dermatologic priority diseases: geometry of randomized trial networks.

    PubMed

    Karimkhani, Chante; Dellavalle, Robert P

    2015-01-01

    This commentary explores the fundamentals of network theory, a branch of applied mathematics that has numerous applications in many fields. Maruani et al. (2014) used network theory to analyze the geometry of the evidence base for dermatologic treatments. This is a prime example of the innovative nature of network theory: the mapping of a complex system into an abstract geometry for easier analysis. The interpretation rests upon the two concepts of diversity and co-occurrence. The mathematical foundation of these concepts is briefly reviewed. In addition, examples of the application of network geometry in other dermatologic settings as well as in science and technology are presented.

  20. Unbundling in Current Broadband and Next-Generation Ultra-Broadband Access Networks

    NASA Astrophysics Data System (ADS)

    Gaudino, Roberto; Giuliano, Romeo; Mazzenga, Franco; Valcarenghi, Luca; Vatalaro, Francesco

    2014-05-01

    This article overviews the methods that are currently under investigation for implementing multi-operator open-access/shared-access techniques in next-generation access ultra-broadband architectures, starting from the traditional "unbundling-of-the-local-loop" techniques implemented in legacy twisted-pair digital subscriber line access networks. A straightforward replication of these copper-based unbundling-of-the-local-loop techniques is usually not feasible on next-generation access networks, including fiber-to-the-home point-to-multipoint passive optical networks. To investigate this issue, the article first gives a concise description of traditional copper-based unbundling-of-the-local-loop solutions, then focalizes on both next-generation access hybrid fiber-copper digital subscriber line fiber-to-the-cabinet scenarios and on fiber to the home by accounting for the mix of regulatory and technological reasons driving the next-generation access migration path, focusing mostly on the European situation.

  1. Fairness problems at the media access level for high-speed networks

    NASA Technical Reports Server (NTRS)

    Maly, Kurt J.; Zhang, L.; Game, David

    1990-01-01

    Most lower speed (approx. 10 Mbps) local area networks use adaptive or random access protocols like Ethernet. Others at higher speed use demand assignment like token or slotted rings. These include Cambridge ring and electronic token ring systems. Fairness issues in representatives of such protocols are discussed. In particular, Fiber Distributed Data Interface (FDDI) was selected as a demand access protocol using tokens, Carrier Sensed Multiple Access/Ring Network (CSMA/RN) a random access protocol, and Distributed Queue Dual Bus (DQDB) a demand access protocol using reservations. Fairness at the media access level was the focus, i.e., attaining access or being excessively delayed when a message is queued to be sent as a function of network location. Within that framework, the essential fairness of FDDI was observed along with severe fairness problems in DQDB and some problems for CSMA/RN. Several modifications were investigated and their ameliorative effect is shown. Finally, a unified presentation which allows comparisons of the three protocols' fairness when normalized to their capacity is given.

  2. Deployment of a Testbed in a Brazilian Research Network using IPv6 and Optical Access Technologies

    NASA Astrophysics Data System (ADS)

    Martins, Luciano; Ferramola Pozzuto, João; Olimpio Tognolli, João; Chaves, Niudomar Siqueira De A.; Reggiani, Atilio Eduardo; Hortêncio, Claudio Antonio

    2012-04-01

    This article presents the implementation of a testbed and the experimental results obtained with it on the Brazilian Experimental Network of the government-sponsored "GIGA Project." The use of IPv6 integrated to current and emerging optical architectures and technologies, such as dense wavelength division multiplexing and 10-gigabit Ethernet on the core and gigabit capable passive optical network and optical distribution network on access, were tested. These protocols, architectures, and optical technologies are promising and part of a brand new worldwide technological scenario that has being fairly adopted in the networks of enterprises and providers of the world.

  3. Setting Access Permission through Transitive Relationship in Web-based Social Networks

    NASA Astrophysics Data System (ADS)

    Hong, Dan; Shen, Vincent Y.

    The rising popularity of various social networking websites has created a huge problem on Internet privacy. Although it is easy to post photos, comments, opinions on some events, etc. on the Web, some of these data (such as a person’s location at a particular time, criticisms of a politician, etc.) are private and should not be accessed by unauthorized users. Although social networks facilitate sharing, the fear of sending sensitive data to a third party without knowledge or permission of the data owners discourages people from taking full advantage of some social networking applications. We exploit the existing relationships on social networks and build a ‘‘trust network’’ with transitive relationship to allow controlled data sharing so that the privacy and preferences of data owners are respected. The trust network linking private data owners, private data requesters, and intermediary users is a directed weighted graph. The permission value for each private data requester can be automatically assigned in this network based on the transitive relationship. Experiments were conducted to confirm the feasibility of constructing the trust network from existing social networks, and to assess the validity of permission value assignments in the query process. Since the data owners only need to define the access rights of their closest contacts once, this privacy scheme can make private data sharing easily manageable by social network participants.

  4. Joint Channel and Network Decoding for XOR-Based Relay in Multi-Access Channel

    NASA Astrophysics Data System (ADS)

    Tang, Suhua; Cheng, Jun; Sun, Chen; Miura, Ryu; Obana, Sadao

    In this paper network coding based relay for multi-access channel is studied. In the system, two nodes send messages to a common access point (AP). A relay assists the two nodes by forwarding a network coded version of the messages. The AP performs joint channel and network decoding to recover the two original messages from three received signals. Two schemes, soft network coding (SoftNC) and turbo network coding (TurboNC), both focusing on bitwise exclusive or (XOR) based network coding, are proposed to salvage messages from erroneous signals. SoftNC is simple and backward compatible with existing protocol stack of wireless networks, and reduces packet errors by maximal ratio combining (MRC). TurboNC improves channel efficiency by letting the relay node transmit only parity check bits of the interleaved XORed message, where reliability is retained by iterative decoding. Simulation results show that compared with the network-layer path diversity scheme [8], both SoftNC and TurboNC greatly improve the reliability, and TurboNC also achieves a much higher throughput. The proposed schemes are suitable for improving the performance of wireless local area networks (WLAN).

  5. Next generation communications satellites: multiple access and network studies

    NASA Technical Reports Server (NTRS)

    Meadows, H. E.; Schwartz, M.; Stern, T. E.; Ganguly, S.; Kraimeche, B.; Matsuo, K.; Gopal, I.

    1982-01-01

    Efficient resource allocation and network design for satellite systems serving heterogeneous user populations with large numbers of small direct-to-user Earth stations are discussed. Focus is on TDMA systems involving a high degree of frequency reuse by means of satellite-switched multiple beams (SSMB) with varying degrees of onboard processing. Algorithms for the efficient utilization of the satellite resources were developed. The effect of skewed traffic, overlapping beams and batched arrivals in packet-switched SSMB systems, integration of stream and bursty traffic, and optimal circuit scheduling in SSMB systems: performance bounds and computational complexity are discussed.

  6. Random access to mobile networks with advanced error correction

    NASA Technical Reports Server (NTRS)

    Dippold, Michael

    1990-01-01

    A random access scheme for unreliable data channels is investigated in conjunction with an adaptive Hybrid-II Automatic Repeat Request (ARQ) scheme using Rate Compatible Punctured Codes (RCPC) Forward Error Correction (FEC). A simple scheme with fixed frame length and equal slot sizes is chosen and reservation is implicit by the first packet transmitted randomly in a free slot, similar to Reservation Aloha. This allows the further transmission of redundancy if the last decoding attempt failed. Results show that a high channel utilization and superior throughput can be achieved with this scheme that shows a quite low implementation complexity. For the example of an interleaved Rayleigh channel and soft decision utilization and mean delay are calculated. A utilization of 40 percent may be achieved for a frame with the number of slots being equal to half the station number under high traffic load. The effects of feedback channel errors and some countermeasures are discussed.

  7. Topic-Aware Physical Activity Propagation in a Health Social Network

    PubMed Central

    Phan, Nhathai; Ebrahimi, Javid; Kil, Dave; Piniewski, Brigitte; Dou, Dejing

    2016-01-01

    Modeling physical activity propagation, such as physical exercise level and intensity, is the key to preventing the conduct that can lead to obesity; it can also help spread wellness behavior in a social network. PMID:27087794

  8. A carrier sensed multiple access protocol for high data base rate ring networks

    NASA Technical Reports Server (NTRS)

    Foudriat, E. C.; Maly, Kurt J.; Overstreet, C. Michael; Khanna, S.; Paterra, Frank

    1990-01-01

    The results of the study of a simple but effective media access protocol for high data rate networks are presented. The protocol is based on the fact that at high data rates networks can contain multiple messages simultaneously over their span, and that in a ring, nodes used to detect the presence of a message arriving from the immediate upstream neighbor. When an incoming signal is detected, the node must either abort or truncate a message it is presently sending. Thus, the protocol with local carrier sensing and multiple access is designated CSMA/RN. The performance of CSMA/RN with TTattempt and truncate is studied using analytic and simulation models. Three performance factors, wait or access time, service time and response or end-to-end travel time are presented. The service time is basically a function of the network rate, it changes by a factor of 1 between no load and full load. Wait time, which is zero for no load, remains small for load factors up to 70 percent of full load. Response time, which adds travel time while on the network to wait and service time, is mainly a function of network length, especially for longer distance networks. Simulation results are shown for CSMA/RN where messages are removed at the destination. A wide range of local and metropolitan area network parameters including variations in message size, network length, and node count are studied. Finally, a scaling factor based upon the ratio of message to network length demonstrates that the results, and hence, the CSMA/RN protocol, are applicable to wide area networks.

  9. ONU power saving modes in next generation optical access networks: progress, efficiency and challenges.

    PubMed

    Dixit, Abhishek; Lannoo, Bart; Colle, Didier; Pickavet, Mario; Demeester, Piet

    2012-12-10

    The optical network unit (ONU), installed at a customer's premises, accounts for about 60% of power in current fiber-to-the-home (FTTH) networks. We propose a power consumption model for the ONU and evaluate the ONU power consumption in various next generation optical access (NGOA) architectures. Further, we study the impact of the power savings of the ONU in various low power modes such as power shedding, doze and sleep.

  10. The PBO Borehole Strainmeter Network: Data Availability, Access And Products

    NASA Astrophysics Data System (ADS)

    Hodgkinson, Kathleen; Mencin, David; Philips, David; Fox, Otina; Henderson, Brent; Meertens, Charles; Mattioli, Glen

    2013-04-01

    Earthscope is a U.S. NSF funded program designed to provide seismic, GPS, strainmeter, fault core, LiDAR, and InSAR data to the scientific community to research the evolution and structure of the North American continent. The Plate Boundary Observatory (PBO), operated by UNAVCO, is the geodetic component of the program. PBO consists of over 1100 continuous GPS sites in the western U.S. and Alaska, 6 long baseline laser strainmeters and 75 co-located borehole strainmeters and seismometers distributed in arrays along the western U.S. Pacific-North American plate boundary. In this presentation we describe how UNAVCO makes the borehole data sets available to the community and details the generation of higher-level PBO strainmeter data products. PBO borehole data flow in either real time or with a few hours delay to the IRIS Data Management Center (DMC) and the Northern California Earthquake Data Center (NCEDC) where they are immediately available in SEED format. Archiving the various data sets using the same, well-known format facilitates the integrated analysis of complementary data sets. Processed strain time-series, earth tide models, barometric pressure response coefficients, long-term borehole trends, data quality information and calibration matrices for each strainmeter are generated by UNAVCO and can accessed in XML format from the DMC and NCEDC or, as ASCII files from UNAVCO. Both formats contain the information required to regenerate the processed time-series from the raw data thus meeting an Earthscope goal of repeatability of processed data sets. UNAVCO is guided by the scientific community in determining the best data formats, archiving, access methods and data products to generate. Recommendations for future data products made in an October 2012 workshop hosted by UNAVCO include: a noise assessment of each strainmeter site, development of a physical model for long-term trends in strainmeter data and the release of high-rate processed data in a seismic data

  11. Efficient traffic grooming with dynamic ONU grouping for multiple-OLT-based access network

    NASA Astrophysics Data System (ADS)

    Zhang, Shizong; Gu, Rentao; Ji, Yuefeng; Wang, Hongxiang

    2015-12-01

    Fast bandwidth growth urges large-scale high-density access scenarios, where the multiple Passive Optical Networking (PON) system clustered deployment can be adopted as an appropriate solution to fulfill the huge bandwidth demands, especially for a future 5G mobile network. However, the lack of interaction between different optical line terminals (OLTs) results in part of the bandwidth resources waste. To increase the bandwidth efficiency, as well as reduce bandwidth pressure at the edge of a network, we propose a centralized flexible PON architecture based on Time- and Wavelength-Division Multiplexing PON (TWDM PON). It can provide flexible affiliation for optical network units (ONUs) and different OLTs to support access network traffic localization. Specifically, a dynamic ONU grouping algorithm (DGA) is provided to obtain the minimal OLT outbound traffic. Simulation results show that DGA obtains an average 25.23% traffic gain increment under different OLT numbers within a small ONU number situation, and the traffic gain will increase dramatically with the increment of the ONU number. As the DGA can be deployed easily as an application running above the centralized control plane, the proposed architecture can be helpful to improve the network efficiency for future traffic-intensive access scenarios.

  12. Impact of green technologies in optical networks case study: green wireless optical broadband access network

    NASA Astrophysics Data System (ADS)

    Puche, William S.; Sierra, Javier E.

    2014-09-01

    This article analyzes the current state of green technologies in optical telecommunications networks, analyzing in detail the basic structure of a hybrid network (Optical-Wireless), taking into account energy consumption by proposing a mathematical model is presented to establish the optimum number of ONUs in a network.

  13. A Stateful Multicast Access Control Mechanism for Future Metro-Area-Networks.

    ERIC Educational Resources Information Center

    Sun, Wei-qiang; Li, Jin-sheng; Hong, Pei-lin

    2003-01-01

    Multicasting is a necessity for a broadband metro-area-network; however security problems exist with current multicast protocols. A stateful multicast access control mechanism, based on MAPE, is proposed. The architecture of MAPE is discussed, as well as the states maintained and messages exchanged. The scheme is flexible and scalable. (Author/AEF)

  14. Incentive Mechanism for P2P Content Sharing over Heterogenous Access Networks

    NASA Astrophysics Data System (ADS)

    Sato, Kenichiro; Hashimoto, Ryo; Yoshino, Makoto; Shinkuma, Ryoichi; Takahashi, Tatsuro

    In peer-to-peer (P2P) content sharing, users can share their content by contributing their own resources to one another. However, since there is no incentive for contributing contents or resources to others, users may attempt to obtain content without any contribution. To motivate users to contribute their resources to the service, incentive-rewarding mechanisms have been proposed. On the other hand, emerging wireless technologies, such as IEEE 802.11 wireless local area networks, beyond third generation (B3G) cellular networks and mobile WiMAX, provide high-speed Internet access for wireless users. Using these high-speed wireless access, wireless users can use P2P services and share their content with other wireless users and with fixed users. However, this diversification of access networks makes it difficult to appropriately assign rewards to each user according to their contributions. This is because the cost necessary for contribution is different in different access networks. In this paper, we propose a novel incentive-rewarding mechanism called EMOTIVER that can assign rewards to users appropriately. The proposed mechanism uses an external evaluator and interactive learning agents. We also investigate a way of appropriately controlling rewards based on the system service's quality and managing policy.

  15. On-demand virtual optical network access using 100 Gb/s Ethernet.

    PubMed

    Ishida, Osamu; Takamichi, Toru; Arai, Sachine; Kawate, Ryusuke; Toyoda, Hidehiro; Morita, Itsuro; Araki, Soichiro; Ichikawa, Toshiyuki; Hoshida, Takeshi; Murai, Hitoshi

    2011-12-12

    Our Terabit LAN initiatives attempt to enhance the scalability and utilization of lambda resources. This paper describes bandwidth-on-demand virtualized 100GE access to WDM networks on a field fiber test-bed using multi-domain optical-path provisioning. PMID:22274022

  16. Assessing Individual Social Capital Capacity: The Development and Validation of a Network Accessibility Scale

    ERIC Educational Resources Information Center

    Hatala, John-Paul

    2009-01-01

    Any organization that is able to promote the importance of increased levels of social capital and individuals who can leverage and use the resources that exist within the network may experience higher levels of performance. This study sought to add to our knowledge about individuals' accessing social resources for the purpose of accomplishing…

  17. A secure WDM ring access network employing silicon micro-ring based remote node

    NASA Astrophysics Data System (ADS)

    Sung, Jiun-Yu; Chow, Chi-Wai; Yeh, Chien-Hung; Xu, Ke; Hsu, Chin-Wei; Su, Hong-Quan; Tsang, Hon-Ki

    2014-08-01

    A secure and scalable wavelength-division-multiplexing (WDM) ring-based access network is proposed and demonstrated using proof-of-concept experiments. In the remote node (RN), wavelength hopping for specific optical networking unit (ONU) is deployed by using silicon micro-ring resonators (SMR). Using silicon-based devices could be cost-effective for the cost-sensitive access network. Hence the optical physical layer security is introduced. The issues of denial of service (DOS) attacks, eavesdropping and masquerading can be made more difficult in the proposed WDM ring-based access network. Besides, the SMRs with different dropped wavelengths can be cascaded, such that the signals pass through the preceding SMRs can be dropped by a succeeding SMR. This can increase the scalability of the RN for supporting more ONUs for future upgrade. Here, error-free 10 Gb/s downlink and 1.25 Gb/s uplink transmission are demonstrated to show the feasibility of the proposed network.

  18. Experimental demonstration of large capacity WSDM optical access network with multicore fibers and advanced modulation formats.

    PubMed

    Li, Borui; Feng, Zhenhua; Tang, Ming; Xu, Zhilin; Fu, Songnian; Wu, Qiong; Deng, Lei; Tong, Weijun; Liu, Shuang; Shum, Perry Ping

    2015-05-01

    Towards the next generation optical access network supporting large capacity data transmission to enormous number of users covering a wider area, we proposed a hybrid wavelength-space division multiplexing (WSDM) optical access network architecture utilizing multicore fibers with advanced modulation formats. As a proof of concept, we experimentally demonstrated a WSDM optical access network with duplex transmission using our developed and fabricated multicore (7-core) fibers with 58.7km distance. As a cost-effective modulation scheme for access network, the optical OFDM-QPSK signal has been intensity modulated on the downstream transmission in the optical line terminal (OLT) and it was directly detected in the optical network unit (ONU) after MCF transmission. 10 wavelengths with 25GHz channel spacing from an optical comb generator are employed and each wavelength is loaded with 5Gb/s OFDM-QPSK signal. After amplification, power splitting, and fan-in multiplexer, 10-wavelength downstream signal was injected into six outer layer cores simultaneously and the aggregation downstream capacity reaches 300 Gb/s. -16 dBm sensitivity has been achieved for 3.8 × 10-3 bit error ratio (BER) with 7% Forward Error Correction (FEC) limit for all wavelengths in every core. Upstream signal from ONU side has also been generated and the bidirectional transmission in the same core causes negligible performance degradation to the downstream signal. As a universal platform for wired/wireless data access, our proposed architecture provides additional dimension for high speed mobile signal transmission and we hence demonstrated an upstream delivery of 20Gb/s per wavelength with QPSK modulation formats using the inner core of MCF emulating a mobile backhaul service. The IQ modulated data was coherently detected in the OLT side. -19 dBm sensitivity has been achieved under the FEC limit and more than 18 dB power budget is guaranteed.

  19. Multi-core fiber technology for highly reliable optical network in access areas

    NASA Astrophysics Data System (ADS)

    Tanaka, Ken-ichi; Lee, Yong; Nomoto, Etsuko; Arimoto, Hideo; Sugawara, Toshiki

    2015-03-01

    A failure recovery system utilizing a multi-core fiber (MCF) link with field programmable gate array-based optical switch units was developed to achieve high capacity and highly reliable optical networks in access areas. We describe the novel MCF link based on a multi-ring structure and a protection scheme to prevent link failures. Fan-in/ -out devices and connectors are also presented to demonstrate the development status of the MCF connection technology for the link. We demonstrated path recovery by switching operation within a sufficiently short time, which is required by ITU-T. The selection of a protecting path as a failure working path was also optimized as the minimum passage of units for low loss transmission. The results we obtained indicate that our proposed link has potential for the network design of highly reliable network topologies in access areas such as data centers, systems in business areas, and fiber to the home systems in residential areas.

  20. A simple, effective media access protocol system for integrated, high data rate networks

    NASA Technical Reports Server (NTRS)

    Foudriat, E. C.; Maly, K.; Overstreet, C. M.; Khanna, S.; Zhang, L.

    1992-01-01

    The operation and performance of a dual media access protocol for integrated, gigabit networks are described. Unlike other dual protocols, each protocol supports a different class of traffic. The Carrier Sensed Multiple Access-Ring Network (CSMA/RN) protocol and the Circulating Reservation Packet (CRP) protocol support asynchronous and synchronous traffic, respectively. The two protocols operate with minimal impact upon each other. Performance information demonstrates that they support a complete range of integrated traffic loads, do not require call setup/termination or a special node for synchronous traffic control, and provide effective pre-use and recovery. The CRP also provides guaranteed access and fairness control for the asynchronous system. The paper demonstrates that the CSMA-CRP system fulfills many of the requirements for gigabit LAN-MAN networks most effectively and simply. To accomplish this, CSMA-CRP features are compared against similar ring and bus systems, such as Cambridge Fast Ring, Metaring, Cyclic Reservation Multiple Access, and Distributed Dual Queue Data Bus (DQDB).

  1. An Adaptive Channel Access Method for Dynamic Super Dense Wireless Sensor Networks

    PubMed Central

    Lei, Chunyang; Bie, Hongxia; Fang, Gengfa; Zhang, Xuekun

    2015-01-01

    Super dense and distributed wireless sensor networks have become very popular with the development of small cell technology, Internet of Things (IoT), Machine-to-Machine (M2M) communications, Vehicular-to-Vehicular (V2V) communications and public safety networks. While densely deployed wireless networks provide one of the most important and sustainable solutions to improve the accuracy of sensing and spectral efficiency, a new channel access scheme needs to be designed to solve the channel congestion problem introduced by the high dynamics of competing nodes accessing the channel simultaneously. In this paper, we firstly analyzed the channel contention problem using a novel normalized channel contention analysis model which provides information on how to tune the contention window according to the state of channel contention. We then proposed an adaptive channel contention window tuning algorithm in which the contention window tuning rate is set dynamically based on the estimated channel contention level. Simulation results show that our proposed adaptive channel access algorithm based on fast contention window tuning can achieve more than 95% of the theoretical optimal throughput and 0.97 of fairness index especially in dynamic and dense networks. PMID:26633421

  2. Quality of Recovery Evaluation of the Protection Schemes for Fiber-Wireless Access Networks

    NASA Astrophysics Data System (ADS)

    Fu, Minglei; Chai, Zhicheng; Le, Zichun

    2016-03-01

    With the rapid development of fiber-wireless (FiWi) access network, the protection schemes have got more and more attention due to the risk of huge data loss when failures occur. However, there are few studies on the performance evaluation of the FiWi protection schemes by the unified evaluation criterion. In this paper, quality of recovery (QoR) method was adopted to evaluate the performance of three typical protection schemes (MPMC scheme, OBOF scheme and RPMF scheme) against the segment-level failure in FiWi access network. The QoR models of the three schemes were derived in terms of availability, quality of backup path, recovery time and redundancy. To compare the performance of the three protection schemes comprehensively, five different classes of network services such as emergency service, prioritized elastic service, conversational service, etc. were utilized by means of assigning different QoR weights. Simulation results showed that, for the most service cases, RPMF scheme was proved to be the best solution to enhance the survivability when planning the FiWi access network.

  3. An Adaptive Channel Access Method for Dynamic Super Dense Wireless Sensor Networks.

    PubMed

    Lei, Chunyang; Bie, Hongxia; Fang, Gengfa; Zhang, Xuekun

    2015-12-03

    Super dense and distributed wireless sensor networks have become very popular with the development of small cell technology, Internet of Things (IoT), Machine-to-Machine (M2M) communications, Vehicular-to-Vehicular (V2V) communications and public safety networks. While densely deployed wireless networks provide one of the most important and sustainable solutions to improve the accuracy of sensing and spectral efficiency, a new channel access scheme needs to be designed to solve the channel congestion problem introduced by the high dynamics of competing nodes accessing the channel simultaneously. In this paper, we firstly analyzed the channel contention problem using a novel normalized channel contention analysis model which provides information on how to tune the contention window according to the state of channel contention. We then proposed an adaptive channel contention window tuning algorithm in which the contention window tuning rate is set dynamically based on the estimated channel contention level. Simulation results show that our proposed adaptive channel access algorithm based on fast contention window tuning can achieve more than 95 % of the theoretical optimal throughput and 0 . 97 of fairness index especially in dynamic and dense networks.

  4. An Adaptive Channel Access Method for Dynamic Super Dense Wireless Sensor Networks.

    PubMed

    Lei, Chunyang; Bie, Hongxia; Fang, Gengfa; Zhang, Xuekun

    2015-01-01

    Super dense and distributed wireless sensor networks have become very popular with the development of small cell technology, Internet of Things (IoT), Machine-to-Machine (M2M) communications, Vehicular-to-Vehicular (V2V) communications and public safety networks. While densely deployed wireless networks provide one of the most important and sustainable solutions to improve the accuracy of sensing and spectral efficiency, a new channel access scheme needs to be designed to solve the channel congestion problem introduced by the high dynamics of competing nodes accessing the channel simultaneously. In this paper, we firstly analyzed the channel contention problem using a novel normalized channel contention analysis model which provides information on how to tune the contention window according to the state of channel contention. We then proposed an adaptive channel contention window tuning algorithm in which the contention window tuning rate is set dynamically based on the estimated channel contention level. Simulation results show that our proposed adaptive channel access algorithm based on fast contention window tuning can achieve more than 95 % of the theoretical optimal throughput and 0 . 97 of fairness index especially in dynamic and dense networks. PMID:26633421

  5. Access, engagement, networks, and norms: Dimensions of social capital at work in a first grade classroom

    NASA Astrophysics Data System (ADS)

    Wexler-Robock, Stephanie

    Social capital refers to access and use of resources available through one's networks to solve problems, and the norms that reflect inclusive or exclusive access to those networks and resources. Research has found positive relationships between social capital, academic achievement, and attainment. Studies, however, have generally examined social capital through factors that occur outside the classroom; students who have social capital, acquired through their family and community relationships, seem to be more successful academically. Limited research has explored what if any factors within the classroom might impact the production, and nature of social capital, or its workings in a classroom. The purpose of this study was to explore the workings and nature of classroom social capital, including its possible relationships to engagement and cognition among 5 student participants. Using methods of qualitative data collection, mixed methods were used to analyze information resources, participants' networking, student work, and classroom discourse. Eight interdependent networking factors and 3 overarching patterns of norms were discovered. The networking factors reflected the structure, content, processes, purposes, and acceptability of participants' networking. The norms, also working interdependently, appeared to promote or inhibit among other things, engagement in networking, help seeking, access, sharing, and intertextual use of diverse, often complex sources of information. Through interaction of the 8 factors and 3 overarching norms, ongoing outcomes of networking appeared to include the creation of bridging (inclusive) and bonding (exclusive) forms of social capital, and depth of scientific conceptual understanding, in this case, about birds. Bridging social capital appeared related to willingness to engage in strong and weak tie networking, help seeking, intertextuality, and possibly to mastery goal orientation for all participants, regardless of reading level

  6. Universal filtered multi-carrier system for asynchronous uplink transmission in optical access network

    NASA Astrophysics Data System (ADS)

    Kang, Soo-Min; Kim, Chang-Hun; Han, Sang-Kook

    2016-02-01

    In passive optical network (PON), orthogonal frequency division multiplexing (OFDM) has been studied actively due to its advantages such as high spectra efficiency (SE), dynamic resource allocation in time or frequency domain, and dispersion robustness. However, orthogonal frequency division multiple access (OFDMA)-PON requires tight synchronization among multiple access signals. If not, frequency orthogonality could not be maintained. Also its sidelobe causes inter-channel interference (ICI) to adjacent channel. To prevent ICI caused by high sidelobes, guard band (GB) is usually used which degrades SE. Thus, OFDMA-PON is not suitable for asynchronous uplink transmission in optical access network. In this paper, we propose intensity modulation/direct detection (IM/DD) based universal filtered multi-carrier (UFMC) PON for asynchronous multiple access. The UFMC uses subband filtering to subsets of subcarriers. Since it reduces sidelobe of each subband by applying subband filtering, it could achieve better performance compared to OFDM. For the experimental demonstration, different sample delay was applied to subbands to implement asynchronous transmission condition. As a result, time synchronization robustness of UFMC was verified in asynchronous multiple access system.

  7. "Current topics in health sciences librarianship": a pilot program for network-based lifelong learning.

    PubMed Central

    Brandt, K A; Sapp, J R; Campbell, J M

    1996-01-01

    The long-term objective of this project is to make health sciences librarians more effective in their role by using emerging technologies to deliver timely continuing education (CE) programs to them regardless of their physical location. The goals of the one-year planning project at the William H. Welch Medical Library are to plan, implement, and evaluate a pilot CE program that includes (1) a three-day general-interest session organized in four tracks: Market Forces and Management, Information Technology and the Internet, Publishing and Copyright, and Education; (2) a one-day special topic session on the Informatics of the Human Genome Project; and (3) an electronic poster session in parallel with the general-interest session. The program will be offered in three simultaneous formats: (1) on-site, in a distance-learning classroom in Baltimore; (2) as a telecourse, in a similar classroom outside Washington, DC; and (3) online, via the World Wide Web. An electronic proceedings of the entire program will be published on the Web to serve as a continuously available CE resource for health sciences librarians. This paper gives an overview of the planning process, presents a status report on the programmatic and technical implementation of the pilot project at its midpoint, and discusses future directions for the program. PMID:8913554

  8. Optical interconnection network for parallel access to multi-rank memory in future computing systems.

    PubMed

    Wang, Kang; Gu, Huaxi; Yang, Yintang; Wang, Kun

    2015-08-10

    With the number of cores increasing, there is an emerging need for a high-bandwidth low-latency interconnection network, serving core-to-memory communication. In this paper, aiming at the goal of simultaneous access to multi-rank memory, we propose an optical interconnection network for core-to-memory communication. In the proposed network, the wavelength usage is delicately arranged so that cores can communicate with different ranks at the same time and broadcast for flow control can be achieved. A distributed memory controller architecture that works in a pipeline mode is also designed for efficient optical communication and transaction address processes. The scaling method and wavelength assignment for the proposed network are investigated. Compared with traditional electronic bus-based core-to-memory communication, the simulation results based on the PARSEC benchmark show that the bandwidth enhancement and latency reduction are apparent.

  9. The Effects of a Dynamic Spectrum Access Overlay in LTE-Advanced Networks

    SciTech Connect

    Juan D. Deaton; Ryan E. Irwin; Luiz A. DaSilva

    2011-05-01

    As early as 2014, mobile network operators’ spectral capacity will be overwhelmed by the demand brought on by new devices and applications. To augment capacity and meet this demand, operators may choose to deploy a Dynamic Spectrum Access (DSA) overlay. The signaling and functionality required by such an overlay have not yet been fully considered in the architecture of the planned Long Term Evolution Advanced (LTE+) networks. This paper presents a Spectrum Accountability framework to be integrated into LTE+ architectures, defining specific element functionality, protocol interfaces, and signaling flow diagrams required to enforce the rights and responsibilities of primary and secondary users. We also quantify, through integer programs, the benefits of using DSA channels to augment capacity under a scenario in which LTE+ network can opportunistically use TV and GSM spectrum. The framework proposed here may serve as a guide in the development of future LTE+ network standards that account for DSA.

  10. Optical interconnection network for parallel access to multi-rank memory in future computing systems.

    PubMed

    Wang, Kang; Gu, Huaxi; Yang, Yintang; Wang, Kun

    2015-08-10

    With the number of cores increasing, there is an emerging need for a high-bandwidth low-latency interconnection network, serving core-to-memory communication. In this paper, aiming at the goal of simultaneous access to multi-rank memory, we propose an optical interconnection network for core-to-memory communication. In the proposed network, the wavelength usage is delicately arranged so that cores can communicate with different ranks at the same time and broadcast for flow control can be achieved. A distributed memory controller architecture that works in a pipeline mode is also designed for efficient optical communication and transaction address processes. The scaling method and wavelength assignment for the proposed network are investigated. Compared with traditional electronic bus-based core-to-memory communication, the simulation results based on the PARSEC benchmark show that the bandwidth enhancement and latency reduction are apparent. PMID:26367901

  11. Satellite-matrix-switched, time-division-multiple-access network simulator

    NASA Technical Reports Server (NTRS)

    Ivancic, William D.; Andro, Monty; Nagy, Lawrence A.; Budinger, James M.; Shalkhauser, Mary JO

    1989-01-01

    A versatile experimental Ka-band network simulator has been implemented at the NASA Lewis Research Center to demonstrate and evaluate a satellite-matrix-switched, time-division-multiple-access (SMS-TDMA) network and to evaluate future digital ground terminals and radiofrequency (RF) components. The simulator was implemented by using proof-of-concept RF components developed under NASA contracts and digital ground terminal and link simulation hardware developed at Lewis. This simulator provides many unique capabilities such as satellite range delay and variation simulation and rain fade simulation. All network parameters (e.g., signal-to-noise ratio, satellite range variation rate, burst density, and rain fade) are controlled and monitored by a central computer. The simulator is presently configured as a three-ground-terminal SMS-TDMA network.

  12. Topology-selective jamming of fully-connected, code-division random-access networks

    NASA Technical Reports Server (NTRS)

    Polydoros, Andreas; Cheng, Unjeng

    1990-01-01

    The purpose is to introduce certain models of topology selective stochastic jamming and examine its impact on a class of fully-connected, spread-spectrum, slotted ALOHA-type random access networks. The theory covers dedicated as well as half-duplex units. The dominant role of the spatial duty factor is established, and connections with the dual concept of time selective jamming are discussed. The optimal choices of coding rate and link access parameters (from the users' side) and the jamming spatial fraction are numerically established for DS and FH spreading.

  13. PANATIKI: A Network Access Control Implementation Based on PANA for IoT Devices

    PubMed Central

    Sanchez, Pedro Moreno; Lopez, Rafa Marin; Gomez Skarmeta, Antonio F.

    2013-01-01

    Internet of Things (IoT) networks are the pillar of recent novel scenarios, such as smart cities or e-healthcare applications. Among other challenges, these networks cover the deployment and interaction of small devices with constrained capabilities and Internet protocol (IP)-based networking connectivity. These constrained devices usually require connection to the Internet to exchange information (e.g., management or sensing data) or access network services. However, only authenticated and authorized devices can, in general, establish this connection. The so-called authentication, authorization and accounting (AAA) services are in charge of performing these tasks on the Internet. Thus, it is necessary to deploy protocols that allow constrained devices to verify their credentials against AAA infrastructures. The Protocol for Carrying Authentication for Network Access (PANA) has been standardized by the Internet engineering task force (IETF) to carry the Extensible Authentication Protocol (EAP), which provides flexible authentication upon the presence of AAA. To the best of our knowledge, this paper is the first deep study of the feasibility of EAP/PANA for network access control in constrained devices. We provide light-weight versions and implementations of these protocols to fit them into constrained devices. These versions have been designed to reduce the impact in standard specifications. The goal of this work is two-fold: (1) to demonstrate the feasibility of EAP/PANA in IoT devices; (2) to provide the scientific community with the first light-weight interoperable implementation of EAP/PANA for constrained devices in the Contiki operating system (Contiki OS), called PANATIKI. The paper also shows a testbed, simulations and experimental results obtained from real and simulated constrained devices. PMID:24189332

  14. PANATIKI: a network access control implementation based on PANA for IoT devices.

    PubMed

    Moreno Sanchez, Pedro; Marin Lopez, Rafa; Gomez Skarmeta, Antonio F

    2013-01-01

    Internet of Things (IoT) networks are the pillar of recent novel scenarios, such as smart cities or e-healthcare applications. Among other challenges, these networks cover the deployment and interaction of small devices with constrained capabilities and Internet protocol (IP)-based networking connectivity. These constrained devices usually require connection to the Internet to exchange information (e.g., management or sensing data) or access network services. However, only authenticated and authorized devices can, in general, establish this connection. The so-called authentication, authorization and accounting (AAA) services are in charge of performing these tasks on the Internet. Thus, it is necessary to deploy protocols that allow constrained devices to verify their credentials against AAA infrastructures. The Protocol for Carrying Authentication for Network Access (PANA) has been standardized by the Internet engineering task force (IETF) to carry the Extensible Authentication Protocol (EAP), which provides flexible authentication upon the presence of AAA. To the best of our knowledge, this paper is the first deep study of the feasibility of EAP/PANA for network access control in constrained devices. We provide light-weight versions and implementations of these protocols to fit them into constrained devices. These versions have been designed to reduce the impact in standard specifications. The goal of this work is two-fold: (1) to demonstrate the feasibility of EAP/PANA in IoT devices; (2) to provide the scientific community with the first light-weight interoperable implementation of EAP/PANA for constrained devices in the Contiki operating system (Contiki OS), called PANATIKI. The paper also shows a testbed, simulations and experimental results obtained from real and simulated constrained devices. PMID:24189332

  15. PANATIKI: a network access control implementation based on PANA for IoT devices.

    PubMed

    Moreno Sanchez, Pedro; Marin Lopez, Rafa; Gomez Skarmeta, Antonio F

    2013-11-01

    Internet of Things (IoT) networks are the pillar of recent novel scenarios, such as smart cities or e-healthcare applications. Among other challenges, these networks cover the deployment and interaction of small devices with constrained capabilities and Internet protocol (IP)-based networking connectivity. These constrained devices usually require connection to the Internet to exchange information (e.g., management or sensing data) or access network services. However, only authenticated and authorized devices can, in general, establish this connection. The so-called authentication, authorization and accounting (AAA) services are in charge of performing these tasks on the Internet. Thus, it is necessary to deploy protocols that allow constrained devices to verify their credentials against AAA infrastructures. The Protocol for Carrying Authentication for Network Access (PANA) has been standardized by the Internet engineering task force (IETF) to carry the Extensible Authentication Protocol (EAP), which provides flexible authentication upon the presence of AAA. To the best of our knowledge, this paper is the first deep study of the feasibility of EAP/PANA for network access control in constrained devices. We provide light-weight versions and implementations of these protocols to fit them into constrained devices. These versions have been designed to reduce the impact in standard specifications. The goal of this work is two-fold: (1) to demonstrate the feasibility of EAP/PANA in IoT devices; (2) to provide the scientific community with the first light-weight interoperable implementation of EAP/PANA for constrained devices in the Contiki operating system (Contiki OS), called PANATIKI. The paper also shows a testbed, simulations and experimental results obtained from real and simulated constrained devices.

  16. A Reinforcement Routing Algorithm with Access Selection in the Multi-Hop Multi-Interface Networks

    NASA Astrophysics Data System (ADS)

    Jafari, Amir Hosein; Shahhoseini, Hadi Shahriar

    2015-03-01

    In this paper, a routing algorithm is proposed for access selection in a network to find the optimal paths among intermediate nodes with multiple interfaces. Markov Decision Process is applied in each node to find optimal policy and select proper paths to the best access point in a dynamic environment. A reward function is defined as environment feedback to optimize and adapt routing behavior of nodes based on the local information. Selection metrics in each node are interface load, link quality and destination condition. It is shown, by using the proposed algorithm, there are better management in the node which decreases interference and collision and selects links with better quality toward the best possible destination. The performance of the method is exemplified and it is shown how the throughput and average delay of the network with more interface in its nodes, improved while packet loss degrades. As an example a two-interface and a one-interface network are studied. It is shown when network load is increased, interface management will improve the throughput, in the network with two-interface nodes. Also, by considering the link quality factor in the reward function, packet dropping becomes less but average delay increases.

  17. BioSYNTHESIS: access to a knowledge network of health sciences databases.

    PubMed

    Broering, N C; Hylton, J S; Guttmann, R; Eskridge, D

    1991-04-01

    Users of the IAIMS Knowledge Network at the Georgetown University Medical Center have access to multiple in-house and external databases from a single point of entry through BioSYNTHESIS. The IAIMS project has developed a rich environment of biomedical information resources that represent a medical decision support system for campus physicians and students. The BioSYNTHESIS system is an information navigator that provides transparent access to a Knowledge Network of over a dozen databases. These multiple health sciences databases consist of bibliographic, informational, diagnostic, and research systems which reside on diverse computers such as DEC VAXs, SUN 490, AT&T 3B2s, Macintoshes, IBM PC/PS2s and the AT&T ISN and SYTEK network systems. Ethernet and TCP/IP protocols are used in the network architecture. BioSYNTHESIS also provides network links to the other campus libraries and to external institutions. As additional knowledge resources and technological advances have become available. BioSYNTHESIS has evolved from a two phase to a three phase program. Major components of the system including recent achievements and future plans are described.

  18. BioSYNTHESIS: access to a knowledge network of health sciences databases.

    PubMed

    Broering, N C; Hylton, J S; Guttmann, R; Eskridge, D

    1991-04-01

    Users of the IAIMS Knowledge Network at the Georgetown University Medical Center have access to multiple in-house and external databases from a single point of entry through BioSYNTHESIS. The IAIMS project has developed a rich environment of biomedical information resources that represent a medical decision support system for campus physicians and students. The BioSYNTHESIS system is an information navigator that provides transparent access to a Knowledge Network of over a dozen databases. These multiple health sciences databases consist of bibliographic, informational, diagnostic, and research systems which reside on diverse computers such as DEC VAXs, SUN 490, AT&T 3B2s, Macintoshes, IBM PC/PS2s and the AT&T ISN and SYTEK network systems. Ethernet and TCP/IP protocols are used in the network architecture. BioSYNTHESIS also provides network links to the other campus libraries and to external institutions. As additional knowledge resources and technological advances have become available. BioSYNTHESIS has evolved from a two phase to a three phase program. Major components of the system including recent achievements and future plans are described. PMID:1661772

  19. Trust-Based Access Control Model from Sociological Approach in Dynamic Online Social Network Environment

    PubMed Central

    Kim, Seungjoo

    2014-01-01

    There has been an explosive increase in the population of the OSN (online social network) in recent years. The OSN provides users with many opportunities to communicate among friends and family. Further, it facilitates developing new relationships with previously unknown people having similar beliefs or interests. However, the OSN can expose users to adverse effects such as privacy breaches, the disclosing of uncontrolled material, and the disseminating of false information. Traditional access control models such as MAC, DAC, and RBAC are applied to the OSN to address these problems. However, these models are not suitable for the dynamic OSN environment because user behavior in the OSN is unpredictable and static access control imposes a burden on the users to change the access control rules individually. We propose a dynamic trust-based access control for the OSN to address the problems of the traditional static access control. Moreover, we provide novel criteria to evaluate trust factors such as sociological approach and evaluate a method to calculate the dynamic trust values. The proposed method can monitor negative behavior and modify access permission levels dynamically to prevent the indiscriminate disclosure of information. PMID:25374943

  20. Trust-based access control model from sociological approach in dynamic online social network environment.

    PubMed

    Baek, Seungsoo; Kim, Seungjoo

    2014-01-01

    There has been an explosive increase in the population of the OSN (online social network) in recent years. The OSN provides users with many opportunities to communicate among friends and family. Further, it facilitates developing new relationships with previously unknown people having similar beliefs or interests. However, the OSN can expose users to adverse effects such as privacy breaches, the disclosing of uncontrolled material, and the disseminating of false information. Traditional access control models such as MAC, DAC, and RBAC are applied to the OSN to address these problems. However, these models are not suitable for the dynamic OSN environment because user behavior in the OSN is unpredictable and static access control imposes a burden on the users to change the access control rules individually. We propose a dynamic trust-based access control for the OSN to address the problems of the traditional static access control. Moreover, we provide novel criteria to evaluate trust factors such as sociological approach and evaluate a method to calculate the dynamic trust values. The proposed method can monitor negative behavior and modify access permission levels dynamically to prevent the indiscriminate disclosure of information.

  1. Performance of a random access packet network with time-capture capability

    NASA Technical Reports Server (NTRS)

    Lin, Y. H.

    1983-01-01

    The Joint Tactical Information Distribution System (JTIDS) is applied to a digital network supporting the command, control and communication requirements of 105 highly mobile users. User data traffic is bursty and the slotted ALOHA channel access scheme is therefore employed. This paper focuses on the determination of JTIDS system performance in this particular application. Emphasis is directed at the specific time-capture capability of JTIDS. Significant system performance parameters are quantified with analysis and simulation.

  2. Metro-access integrated network based on optical OFDMA with dynamic sub-carrier allocation and power distribution.

    PubMed

    Zhang, Chongfu; Zhang, Qiongli; Chen, Chen; Jiang, Ning; Liu, Deming; Qiu, Kun; Liu, Shuang; Wu, Baojian

    2013-01-28

    We propose and demonstrate a novel optical orthogonal frequency-division multiple access (OFDMA)-based metro-access integrated network with dynamic resource allocation. It consists of a single fiber OFDMA ring and many single fiber OFDMA trees, which transparently integrates metropolitan area networks with optical access networks. The single fiber OFDMA ring connects the core network and the central nodes (CNs), the CNs are on demand reconfigurable and use multiple orthogonal sub-carriers to realize parallel data transmission and dynamic resource allocation, meanwhile, they can also implement flexible power distribution. The remote nodes (RNs) distributed in the user side are connected by the single fiber OFDMA trees with the corresponding CN. The obtained results indicate that our proposed metro-access integrated network is feasible and the power distribution is agile.

  3. Multi-channel access technology based on wavelength division multiplexing in wireless UV communication mesh network

    NASA Astrophysics Data System (ADS)

    Zhao, Tai-fei; Zhang, Ai-li; Xue, Rong-li

    2013-05-01

    In this paper, the multi-channel access technology of wavelength division multiplexing (WDM) in the wireless ultraviolet (UV) scattering communication is studied. A multi-interface and multi-channel device is deployed in each UV transceiver node. The band-pass filter is configured in the receiving node so as to realize the multi-channel access by use of the UV WDM technology. Both the UV communication node model and the UV channel model are established. Three types of UV no-line-of-sight (NLOS) multi-channel communications are simulated in the mesh topologies with NS2. The results show that the UV multi-channel access technology can increase network throughput effectively with using WDM.

  4. Multicore fronthaul and backhaul provision in next-generation optical access networks

    NASA Astrophysics Data System (ADS)

    Llorente, Roberto; Morant, Maria; Macho, Andrés.

    2016-02-01

    This paper reports the experimental demonstration of a multicore fiber (MCF) system employing space-division multiplexing for the combined transmission of radio-over-fiber full-standard LTE-Advanced and WiMAX signals in a 4-core MCF optical fronthaul on a PON access network. Combining MCF fronthaul and PON access with RoF transmission enables the simultaneous transmission of downstream and upstream services in different cores. In this work, we propose and demonstrate a MCF fronthaul system providing combined fully-standard LTE-A and WiMAX signals using radio-over-fiber (RoF) transmission in a 4-core MCF media. The impact of the inter-core crosstalk in RoF transmissions is also evaluated and we studied the possibility of mitigating the crosstalk impairments with MIMO processing. The experimental performance of the PON access overlay employing optical polarization multiplexing is also reported.

  5. Assessment of micro-regional internal accessibility based on road network

    NASA Astrophysics Data System (ADS)

    Nie, Ting; Li, Manchun; Jiang, Zhixin; Huang, Kang

    2007-06-01

    Accessibility is an important indicator of regional land-use, social justice and quality of life. It means the convenience from one place to another in a specified kind of transportation system. Wide-region based, most of the present domestic accessibility research took the high-grade highway such as highway and railway as entirely open road, without considering the service that high-grade highway provides based on intersection and railway station. This study extended to put forward arithmetic to deal with this problem in a micro-regional study area. Taking New District, Wuxi City, Jiangsu Province as a study case, this study researched the assessment of micro-regional internal accessibility based on road network including closed road. This study provides a tool to regional economical and social decision, and introduces a new view for studying relationship between people and land-use in micro-district.

  6. Pace: Privacy-Protection for Access Control Enforcement in P2P Networks

    NASA Astrophysics Data System (ADS)

    Sánchez-Artigas, Marc; García-López, Pedro

    In open environments such as peer-to-peer (P2P) systems, the decision to collaborate with multiple users — e.g., by granting access to a resource — is hard to achieve in practice due to extreme decentralization and the lack of trusted third parties. The literature contains a plethora of applications in which a scalable solution for distributed access control is crucial. This fact motivates us to propose a protocol to enforce access control, applicable to networks consisting entirely of untrusted nodes. The main feature of our protocol is that it protects both sensitive permissions and sensitive policies, and does not rely on any centralized authority. We analyze the efficiency (computational effort and communication overhead) as well as the security of our protocol.

  7. Virtual shelves in a digital library: a framework for access to networked information sources.

    PubMed Central

    Patrick, T B; Springer, G K; Mitchell, J A; Sievert, M E

    1995-01-01

    OBJECTIVE: Develop a framework for collections-based access to networked information sources that addresses the problem of location-dependent access to information sources. DESIGN: This framework uses a metaphor of a virtual shelf. A virtual shelf is a general-purpose server that is dedicated to a particular information subject class. The identifier of one of these servers identifies its subject class. Location-independent call numbers are assigned to information sources. Call numbers are based on standard vocabulary codes. The call numbers are first mapped to the location-independent identifiers of virtual shelves. When access to an information resource is required, a location directory provides a second mapping of these location-independent server identifiers to actual network locations. RESULTS: The framework has been implemented in two different systems. One system is based on the Open System Foundation/Distributed Computing Environment and the other is based on the World Wide Web. CONCLUSIONS: This framework applies in new ways traditional methods of library classification and cataloging. It is compatible with two traditional styles of selecting information searching and browsing. Traditional methods may be combined with new paradigms of information searching that will be able to take advantage of the special properties of digital information. Cooperation between the library-informational science community and the informatics community can provide a means for a continuing application of the knowledge and techniques of library science to the new problems of networked information sources. PMID:8581554

  8. Energy-efficient rings mechanism for greening multisegment fiber-wireless access networks

    NASA Astrophysics Data System (ADS)

    Gong, Xiaoxue; Guo, Lei; Hou, Weigang; Zhang, Lincong

    2013-07-01

    Through integrating advantages of optical and wireless communications, the Fiber-Wireless (FiWi) has become a promising solution for the "last-mile" broadband access. In particular, greening FiWi has attained extensive attention, because the access network is a main energy contributor in the whole infrastructure. However, prior solutions of greening FiWi shut down or sleep unused/minimally used optical network units for a single segment, where we deploy only one optical linear terminal. We propose a green mechanism referred to as energy-efficient ring (EER) for multisegment FiWi access networks. We utilize an integer linear programming model and a generic algorithm to generate clusters, each having the shortest distance of fully connected segments of its own. Leveraging the backtracking method for each cluster, we then connect segments through fiber links, and the shortest distance fiber ring is constructed. Finally, we sleep low load segments and forward affected traffic to other active segments on the same fiber ring by our sleeping scheme. Experimental results show that our EER mechanism significantly reduces the energy consumption at the slightly additional cost of deploying fiber links.

  9. Optimization of broadband optical access networks for residential and small-business users

    NASA Astrophysics Data System (ADS)

    Andersen, Niels E.

    1997-10-01

    The broadband loop project is a joint European project which is developing low cost access network solutions for competitive access providers. The project is developing passive optical network (PON) solutions optimized for delivery of services in low penetrated areas. The basic version of the PON is a SDH PON which can provide managed SDH transport to the customers premises. ATM can be provided via the SDH PON system. The PON bandwidth can be gracefully extended from 155 Mbit/s bidirectionally up to provide 1 Gbit/s in the downstream direction and 576 Mbit/s in the upstream direction. Subcarrier multiplexing is used to extend the bandwidth. Digital subscriber line (DSL) technology is used to provide broadband services over existing copper wires. The project is evaluating the tradeoff between use of optical fiber or copper in the access network. Life cycle cost studies compares different deployment scenarios for business and residential subscribers. Field trials are installed in Denmark, Portugal and Poland in order to evaluate the system under real life conditions.

  10. Delay analysis of an integrated voice and data access protocol with collision detection for multimedia satellite networks

    NASA Astrophysics Data System (ADS)

    Poon, Charles C. K.; Suda, Tatsuya

    1992-03-01

    The novel multiple-access scheme for multimedia satellite networks presented is based on a combination of FDMA and TDMA, integrating both circuit and packet-switching techniques. While the circuit-switching method is used to transmit such stream-type traffic as real-time voice communications, packet-switching is used to transmit such 'bursty' traffic as interactive data. A ground radio network is assumed for control signaling; the tone sense multiple access/partial collision detection scheme is implemented on this network to enhance the integrated access scheme's performance.

  11. Support networks and people with physical disabilities: social inclusion and access to health services.

    PubMed

    Holanda, Cristina Marques de Almeida; De Andrade, Fabienne Louise Juvêncio Paes; Bezerra, Maria Aparecida; Nascimento, João Paulo da Silva; Neves, Robson da Fonseca; Alves, Simone Bezerra; Ribeiro, Kátia Suely Queiroz Silva

    2015-01-01

    This study seeks to identify the formation of social support networks of people with physical disabilities, and how these networks can help facilitate access to health services and promote social inclusion. It is a cross-sectional study, with data collected via a form applied to physically disabled persons over eighteen years of age registered with the Family Health Teams of the municipal district of João Pessoa in the state of Paraíba. It was observed that the support networks of these individuals predominantly consist of family members (parents, siblings, children, spouses) and people outside the family (friends and neighbors). However, 50% of the interviewees declared that they could not count on any support from outside the family. It was observed that the support network contributes to access to the services and participation in social groups. However, reduced social inclusion was detected, due to locomotion difficulties, this being the main barrier to social interaction. Among those individuals who began to interact in society, the part played by social support was fundamental.

  12. SAHBNET, an Accessible Surface-Based Elastic Network: An Application to Membrane Protein

    PubMed Central

    Dony, Nicolas; Crowet, Jean Marc; Joris, Bernard; Brasseur, Robert; Lins, Laurence

    2013-01-01

    Molecular Dynamics is a method of choice for membrane simulations and the rising of coarse-grained forcefields has opened the way to longer simulations with reduced calculations times. Here, we present an elastic network, SAHBNET (Surface Accessibility Hydrogen-Bonds elastic NETwork), that will maintain the structure of soluble or membrane proteins based on the hydrogen bonds present in the atomistic structure and the proximity between buried residues. This network is applied on the coarse-grained beads defined by the MARTINI model, and was designed to be more physics-based than a simple elastic network. The SAHBNET model is evaluated against atomistic simulations, and compared with ELNEDYN models. The SAHBNET is then used to simulate two membrane proteins inserted in complex lipid bilayers. These bilayers are formed by self-assembly and the use of a modified version of the GROMACS tool genbox (which is accessible through the gcgs.gembloux.ulg.ac.be website). The results show that SAHBNET keeps the structure close to the atomistic one and is successfully used for the simulation of membrane proteins. PMID:23722660

  13. The Effects of a Dynamic Spectrum Access Overlay in LTE-Advanced Networks

    SciTech Connect

    Juan D. Deaton; Ryan E. lrwin; Luiz A. DaSilva

    2011-05-01

    As early as 2014, wireless network operators spectral capacity will be overwhelmed by a data tsunami brought on by new devices and applications. To augment spectral capacity, operators could deploy a Dynamic Spectrum Access (DSA) overlay. In the light of the many planned Long Term Evolution (LTE) network deployments, the affects of a DSA overlay have not been fully considered into the existing LTE standards. Coalescing many different aspects of DSA, this paper develops the Spectrum Accountability (SA) framework. The SA framework defines specific network element functionality, protocol interfaces, and signaling flow diagrams for LTE to support service requests and enforce rights of responsibilities of primary and secondary users, respectively. We also include a network simulation to quantify the benefits of using DSA channels to augment capacity. Based on our simulation we show that, network operators can benefit up to %40 increase in operating capacity when sharing DSA bands to augment spectral capacity. With our framework, this paper could serve as an guide in developing future LTE network standards that include DSA.

  14. Modeling Social Capital as Dynamic Networks to Promote Access to Oral Healthcare

    PubMed Central

    Northridge, Mary E.; Kunzel, Carol; Zhang, Qiuyi; Kum, Susan S.; Gilbert, Jessica L.; Jin, Zhu; Metcalf, Sara S.

    2016-01-01

    Social capital, as comprised of human connections in social networks and their associated benefits, is closely related to the health of individuals, communities, and societies at large. For disadvantaged population groups such as older adults and racial/ethnic minorities, social capital may play a particularly critical role in mitigating the negative effects and reinforcing the positive effects on health. In this project, we model social capital as both cause and effect by simulating dynamic networks. Informed in part by a community-based health promotion program, an agent-based model is contextualized in a GIS environment to explore the complexity of social disparities in oral and general health as experienced at the individual, interpersonal, and community scales. This study provides the foundation for future work investigating how health and healthcare accessibility may be influenced by social networks.

  15. A Scalable Long-Reach Wavelength-Division Multiplexing Access Network Sharing Both Fiber Protection and Broadcasting Services

    NASA Astrophysics Data System (ADS)

    Feng, Chen; Gan, Chaoqin; Gao, Ziyue; Guo, Su; Li, Wei; Fang, Yiqin

    2014-07-01

    A novel scalable wavelength-division multiplexing access network is proposed in this article. By newly designing the remote node, this network can not only support the long-reach transmission and broadcasting services, it can also have flexible scalability and the ability of sharing fiber protection. These make this network have great resilient capability. Also, this scheme still has the characteristic of Rayleigh backscattering mitigation and shared-seeding light of upstream signals. The simulation results indicate this network has good performance.

  16. Adaptation of AMO-FBMC-OQAM in optical access network for accommodating asynchronous multiple access in OFDM-based uplink transmission

    NASA Astrophysics Data System (ADS)

    Jung, Sun-Young; Jung, Sang-Min; Han, Sang-Kook

    2015-01-01

    Exponentially expanding various applications in company with proliferation of mobile devices make mobile traffic exploded annually. For future access network, bandwidth efficient and asynchronous signals converged transmission technique is required in optical network to meet a huge bandwidth demand, while integrating various services and satisfying multiple access in perceived network resource. Orthogonal frequency division multiplexing (OFDM) is highly bandwidth efficient parallel transmission technique based on orthogonal subcarriers. OFDM has been widely studied in wired-/wireless communication and became a Long term evolution (LTE) standard. Consequently, OFDM also has been actively researched in optical network. However, OFDM is vulnerable frequency and phase offset essentially because of its sinc-shaped side lobes, therefore tight synchronism is necessary to maintain orthogonality. Moreover, redundant cyclic prefix (CP) is required in dispersive channel. Additionally, side lobes act as interference among users in multiple access. Thus, it practically hinders from supporting integration of various services and multiple access based on OFDM optical transmission In this paper, adaptively modulated optical filter bank multicarrier system with offset QAM (AMO-FBMC-OQAM) is introduced and experimentally investigated in uplink optical transmission to relax multiple access interference (MAI), while improving bandwidth efficiency. Side lobes are effectively suppressed by using FBMC, therefore the system becomes robust to path difference and imbalance among optical network units (ONUs), which increase bandwidth efficiency by reducing redundancy. In comparison with OFDM, a signal performance and an efficiency of frequency utilization are improved in the same experimental condition. It enables optical network to effectively support heterogeneous services and multiple access.

  17. Basset: learning the regulatory code of the accessible genome with deep convolutional neural networks

    PubMed Central

    Kelley, David R.; Snoek, Jasper; Rinn, John L.

    2016-01-01

    The complex language of eukaryotic gene expression remains incompletely understood. Despite the importance suggested by many noncoding variants statistically associated with human disease, nearly all such variants have unknown mechanisms. Here, we address this challenge using an approach based on a recent machine learning advance—deep convolutional neural networks (CNNs). We introduce the open source package Basset to apply CNNs to learn the functional activity of DNA sequences from genomics data. We trained Basset on a compendium of accessible genomic sites mapped in 164 cell types by DNase-seq, and demonstrate greater predictive accuracy than previous methods. Basset predictions for the change in accessibility between variant alleles were far greater for Genome-wide association study (GWAS) SNPs that are likely to be causal relative to nearby SNPs in linkage disequilibrium with them. With Basset, a researcher can perform a single sequencing assay in their cell type of interest and simultaneously learn that cell's chromatin accessibility code and annotate every mutation in the genome with its influence on present accessibility and latent potential for accessibility. Thus, Basset offers a powerful computational approach to annotate and interpret the noncoding genome. PMID:27197224

  18. Basset: learning the regulatory code of the accessible genome with deep convolutional neural networks.

    PubMed

    Kelley, David R; Snoek, Jasper; Rinn, John L

    2016-07-01

    The complex language of eukaryotic gene expression remains incompletely understood. Despite the importance suggested by many noncoding variants statistically associated with human disease, nearly all such variants have unknown mechanisms. Here, we address this challenge using an approach based on a recent machine learning advance-deep convolutional neural networks (CNNs). We introduce the open source package Basset to apply CNNs to learn the functional activity of DNA sequences from genomics data. We trained Basset on a compendium of accessible genomic sites mapped in 164 cell types by DNase-seq, and demonstrate greater predictive accuracy than previous methods. Basset predictions for the change in accessibility between variant alleles were far greater for Genome-wide association study (GWAS) SNPs that are likely to be causal relative to nearby SNPs in linkage disequilibrium with them. With Basset, a researcher can perform a single sequencing assay in their cell type of interest and simultaneously learn that cell's chromatin accessibility code and annotate every mutation in the genome with its influence on present accessibility and latent potential for accessibility. Thus, Basset offers a powerful computational approach to annotate and interpret the noncoding genome. PMID:27197224

  19. Basset: learning the regulatory code of the accessible genome with deep convolutional neural networks.

    PubMed

    Kelley, David R; Snoek, Jasper; Rinn, John L

    2016-07-01

    The complex language of eukaryotic gene expression remains incompletely understood. Despite the importance suggested by many noncoding variants statistically associated with human disease, nearly all such variants have unknown mechanisms. Here, we address this challenge using an approach based on a recent machine learning advance-deep convolutional neural networks (CNNs). We introduce the open source package Basset to apply CNNs to learn the functional activity of DNA sequences from genomics data. We trained Basset on a compendium of accessible genomic sites mapped in 164 cell types by DNase-seq, and demonstrate greater predictive accuracy than previous methods. Basset predictions for the change in accessibility between variant alleles were far greater for Genome-wide association study (GWAS) SNPs that are likely to be causal relative to nearby SNPs in linkage disequilibrium with them. With Basset, a researcher can perform a single sequencing assay in their cell type of interest and simultaneously learn that cell's chromatin accessibility code and annotate every mutation in the genome with its influence on present accessibility and latent potential for accessibility. Thus, Basset offers a powerful computational approach to annotate and interpret the noncoding genome.

  20. Advanced digital signal processing for short-haul and access network

    NASA Astrophysics Data System (ADS)

    Zhang, Junwen; Yu, Jianjun; Chi, Nan

    2016-02-01

    Digital signal processing (DSP) has been proved to be a successful technology recently in high speed and high spectrum-efficiency optical short-haul and access network, which enables high performances based on digital equalizations and compensations. In this paper, we investigate advanced DSP at the transmitter and receiver side for signal pre-equalization and post-equalization in an optical access network. A novel DSP-based digital and optical pre-equalization scheme has been proposed for bandwidth-limited high speed short-distance communication system, which is based on the feedback of receiver-side adaptive equalizers, such as least-mean-squares (LMS) algorithm and constant or multi-modulus algorithms (CMA, MMA). Based on this scheme, we experimentally demonstrate 400GE on a single optical carrier based on the highest ETDM 120-GBaud PDM-PAM-4 signal, using one external modulator and coherent detection. A line rate of 480-Gb/s is achieved, which enables 20% forward-error correction (FEC) overhead to keep the 400-Gb/s net information rate. The performance after fiber transmission shows large margin for both short range and metro/regional networks. We also extend the advanced DSP for short haul optical access networks by using high order QAMs. We propose and demonstrate a high speed multi-band CAP-WDM-PON system on intensity modulation, direct detection and digital equalizations. A hybrid modified cascaded MMA post-equalization schemes are used to equalize the multi-band CAP-mQAM signals. Using this scheme, we successfully demonstrates 550Gb/s high capacity WDMPON system with 11 WDM channels, 55 sub-bands, and 10-Gb/s per user in the downstream over 40-km SMF.

  1. Pharma Pricing & Market Access Europe 2016--Health Network Communications' Tenth Annual Conference (February 23-25, 2016--London, UK).

    PubMed

    D'Souza, P

    2016-03-01

    Tighter national budgets and escalating drug prices continue to present challenges for pharmaceutical market access strategies and societal cost of care. As pharmaceutical companies and medical governmental advisory organizations enter tougher negotiations, hospital trusts and other dispensary firms face barriers to receiving the best medical treatment, and as a result patient access is limited. The 2016 HealthNetwork Communications' Pharma Pricing & Market Access Europe meeting brought together pharmaceutical, medical governmental advisory and stakeholders and market access/pricing consultants, to encourage discussions and negotiations into how to improve the drug pricing system and consequential market access strategies while achieving the respective reimbursement and affordability objectives. PMID:27186595

  2. Pharma Pricing & Market Access Europe 2016--Health Network Communications' Tenth Annual Conference (February 23-25, 2016--London, UK).

    PubMed

    D'Souza, P

    2016-03-01

    Tighter national budgets and escalating drug prices continue to present challenges for pharmaceutical market access strategies and societal cost of care. As pharmaceutical companies and medical governmental advisory organizations enter tougher negotiations, hospital trusts and other dispensary firms face barriers to receiving the best medical treatment, and as a result patient access is limited. The 2016 HealthNetwork Communications' Pharma Pricing & Market Access Europe meeting brought together pharmaceutical, medical governmental advisory and stakeholders and market access/pricing consultants, to encourage discussions and negotiations into how to improve the drug pricing system and consequential market access strategies while achieving the respective reimbursement and affordability objectives.

  3. Wide area network access to CMS data using the LustreTM filesystem

    NASA Astrophysics Data System (ADS)

    Rodriguez, J. L.; Avery, P.; Brody, T.; Bourilkov, D.; Fu, Y.; Kim, B.; Prescott, C.; Wu, Y.

    2010-04-01

    In this paper, we explore the use of the LustreTM cluster filesystem over the wide area network to access Compact Muon Solenoid (CMS) data stored on physical devices located hundreds of kilometres away. We describe the experimental testbed and report on the I/O performance of applications writing and reading data on the distributed LustreTM filesystem established across the WAN. We compare the I/O performance of a CMS application to the performance obtained with IOzone, a standard benchmark tool. We then examine the I/O performance of the CMS application running multiple processes on a single server. And compare the Lustre results to results obtained on data stored on local filesystems. Our measurements reveal that the IOzone benchmark tool, accessing data sequentially, can saturate the Gbps network link that connects our Lustre client in Miami Florida to the Lustre storage located in Gainesville, Florida. We also find that the I/O rates of the CMS application is significantly less than what can be obtained with IOzone for sequential access to data.

  4. A Time-constrained Network Voronoi Construction and Accessibility Analysis in Location-based Service Technology

    NASA Astrophysics Data System (ADS)

    Yu, W.; Ai, T.

    2014-11-01

    Accessibility analysis usually requires special models of spatial location analysis based on some geometric constructions, such as Voronoi diagram (abbreviated to VD). There are many achievements in classic Voronoi model research, however suffering from the following limitations for location-based services (LBS) applications. (1) It is difficult to objectively reflect the actual service areas of facilities by using traditional planar VDs, because human activities in LBS are usually constrained only to the network portion of the planar space. (2) Although some researchers have adopted network distance to construct VDs, their approaches are used in a static environment, where unrealistic measures of shortest path distance based on assumptions about constant travel speeds through the network were often used. (3) Due to the computational complexity of the shortest-path distance calculating, previous researches tend to be very time consuming, especially for large datasets and if multiple runs are required. To solve the above problems, a novel algorithm is developed in this paper. We apply network-based quadrat system and 1-D sequential expansion to find the corresponding subnetwork for each focus. The idea is inspired by the natural phenomenon that water flow extends along certain linear channels until meets others or arrives at the end of route. In order to accommodate the changes in traffic conditions, the length of network-quadrat is set upon the traffic condition of the corresponding street. The method has the advantage over Dijkstra's algorithm in that the time cost is avoided, and replaced with a linear time operation.

  5. Enabling Broadband as Commodity within Access Networks: A QoS Recipe

    NASA Astrophysics Data System (ADS)

    Areizaga, Enrique; Foglar, Andreas; Elizondo, Antonio J.; Geilhardt, Frank

    This paper describes the QoS features that will transform the access networks landscape in order to bring “Broadband” as a commodity while setting up the pillars of the “Future Media Internet”. Quality of Experience is obviously key for emerging and future services. Broadcasting services will first need to equal the QoE of their counterparts in the Open-air market (for IP-TV examples would be artifact-free, no picture freezing, fast zapping times) and offer new features often using interactivity (Time-shifted TV, access to more content, 3DTV with feeling of presence). The huge variety of communications alternatives will lead to different requirements per customer, whose needs will also be dependent on parameters like where the connection is made, the time of the day/day of the week/period of the year or even his/her mood. Today’s networks, designed for providing just Broadband connectivity, will not be enough to satisfy customer’s needs and will necessarily support the introduction of new and innovative services. The Networks of the future should learn from the way the users are communicating, what services they are using, where, when, and how, and adapt accordingly.

  6. Secure wide area network access to CMS analysis data using the Lustre filesystem

    NASA Astrophysics Data System (ADS)

    Bourilkov, D.; Avery, P.; Cheng, M.; Fu, Y.; Kim, B.; Palencia, J.; Budden, R.; Benninger, K.; Rodriquez, J. L.; Dilascio, J.; Dykstra, D.; Seenu, N.

    2012-12-01

    This paper reports the design and implementation of a secure, wide area network (WAN), distributed filesystem by the ExTENCI project (Extending Science Through Enhanced National CyberInfrastructure), based on the Lustre filesystem. The system is used for remote access to analysis data from the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC), and from the Lattice Quantum ChromoDynamics (LQCD) project. Security is provided by Kerberos authentication and authorization with additional fine grained control based on Lustre ACLs (Access Control List) and quotas. We investigate the impact of using various Kerberos security flavors on the I/O rates of CMS applications on client nodes reading and writing data to the Lustre filesystem, and on LQCD benchmarks. The clients can be real or virtual nodes. We are investigating additional options for user authentication based on user certificates.

  7. 42 CFR 423.124 - Special rules for out-of-network access to covered Part D drugs at out-of-network pharmacies.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 3 2011-10-01 2011-10-01 false Special rules for out-of-network access to covered Part D drugs at out-of-network pharmacies. 423.124 Section 423.124 Public Health CENTERS FOR MEDICARE... PRESCRIPTION DRUG BENEFIT Benefits and Beneficiary Protections § 423.124 Special rules for...

  8. 42 CFR 423.124 - Special rules for out-of-network access to covered Part D drugs at out-of-network pharmacies.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 3 2010-10-01 2010-10-01 false Special rules for out-of-network access to covered Part D drugs at out-of-network pharmacies. 423.124 Section 423.124 Public Health CENTERS FOR MEDICARE... PRESCRIPTION DRUG BENEFIT Benefits and Beneficiary Protections § 423.124 Special rules for...

  9. Recent advances on optical reflectometry for access network diagnostics and distributed sensing

    NASA Astrophysics Data System (ADS)

    He, Zuyuan; Fan, Xinyu; Liu, Qingwen; Du, Jiangbing

    2015-07-01

    In this invited talk, we will present the advances in research and development activities of optical reflectometry in our laboratory. The performance of phase-sensitive coherent OTDR, which is developed for distributed vibration measurement, is reported with the results of field tests. The performance of time-gated digital OFDR, which is developed for optical access network diagnostics, is also reported. We will also discuss how to increase the frequency sweep span of the linearly-swept optical source, a very important part for improving the performance of optical reflectometry.

  10. Sub-THz photonic frequency conversion using optoelectronic transistors for future fully coherent access network systems

    NASA Astrophysics Data System (ADS)

    Otsuji, Taiichi; Sugawara, Kenta; Tamamushi, Gen; Dobroiu, Adrian; Suemitsu, Tetsuya; Ryzhii, Victor; Iwatsuki, Katsumi; Kuwano, Shigeru; Kani, Jun-ichi; Terada, Jun

    2016-02-01

    This paper reviews advances in sub-THz photonic frequency conversion using optoelectronic transistors for future fully coherent access network systems. Graphene-channel field effect transistors (G-FETs) and InP-based high electron mobility transistors (inP-HEMT) are experimentally examined as photonic frequency converters. Optoelectronic properties and three-terminal functionalities of the G-FETs and InP-HEMTs are exploited to perform single-chip photonic double-mixing operation over the 120 GHz wireless communication band. A single transistor can photomix the optical subcarriers to generate LO and mix down the RF data on the sub-THz carrier to the IF band.

  11. Seamless generation and provisioning of broadcasting and independent services in WDMPON access networks.

    PubMed

    Tang, Ming; Fu, Songnian; Shum, Perry Ping

    2009-06-01

    A novel broadcasting scheme for WDM-PON based fiber access networks is proposed in this paper and downstream system experiments has been demonstrated. The broadcasting data is generated via subcarrier modulation technique. By using a delayed interferometer, the un-modulated continuous-wave carrier is separated and acts as the seeder for FP-LD injection locking and direct modulation, which is compatible with current WDM-PON infrastructures. In experiments, 2.5 Gb/s broadcasting data and 2.5 Gb/s point-to-point data are successfully integrated and transmitted in a typical WDM-PON structure with good performance.

  12. Seamless generation and provisioning of broadcasting and independent services in WDMPON access networks.

    PubMed

    Tang, Ming; Fu, Songnian; Shum, Perry Ping

    2009-06-01

    A novel broadcasting scheme for WDM-PON based fiber access networks is proposed in this paper and downstream system experiments has been demonstrated. The broadcasting data is generated via subcarrier modulation technique. By using a delayed interferometer, the un-modulated continuous-wave carrier is separated and acts as the seeder for FP-LD injection locking and direct modulation, which is compatible with current WDM-PON infrastructures. In experiments, 2.5 Gb/s broadcasting data and 2.5 Gb/s point-to-point data are successfully integrated and transmitted in a typical WDM-PON structure with good performance. PMID:19506612

  13. A Cloud-Assisted Random Linear Network Coding Medium Access Control Protocol for Healthcare Applications

    PubMed Central

    Kartsakli, Elli; Antonopoulos, Angelos; Alonso, Luis; Verikoukis, Christos

    2014-01-01

    Relay sensor networks are often employed in end-to-end healthcare applications to facilitate the information flow between patient worn sensors and the medical data center. Medium access control (MAC) protocols, based on random linear network coding (RLNC), are a novel and suitable approach to efficiently handle data dissemination. However, several challenges arise, such as additional delays introduced by the intermediate relay nodes and decoding failures, due to channel errors. In this paper, we tackle these issues by adopting a cloud architecture where the set of relays is connected to a coordinating entity, called cloud manager. We propose a cloud-assisted RLNC-based MAC protocol (CLNC-MAC) and develop a mathematical model for the calculation of the key performance metrics, namely the system throughput, the mean completion time for data delivery and the energy efficiency. We show the importance of central coordination in fully exploiting the gain of RLNC under error-prone channels. PMID:24618727

  14. Experimental demonstration of a low-cost tunable semiconductor DFB laser for access networks

    NASA Astrophysics Data System (ADS)

    Li, Lianyan; Tang, Song; Huang, Long; Zhang, Tingting; Li, Simin; Shi, Yuechun; Chen, Xiangfei

    2014-09-01

    A low-cost tunable semiconductor distributed feedback (DFB) laser design in access networks is proposed and experimentally demonstrated. It covers 9 nm continuous tuning range by changing the temperature. The side mode suppression ratios are above 42 dB over the tuning range. The current and temperature coefficients of wavelength tuning are 0.0124 nm mA-1 and 0.0875 nm °C, respectively. The results indicate that the reconstruction-equivalent-chirp (REC) technique is promising to fabricate low-cost tunable DFB lasers meeting the requirement of wavelength-division-multiplexing passive optical networks (WDM-PONs). It should be also noted that the tuning range can be easily extended by using more sections.

  15. A Time Tree Medium Access Control for Energy Efficiency and Collision Avoidance in Wireless Sensor Networks

    PubMed Central

    Lee, Kilhung

    2010-01-01

    This paper presents a medium access control and scheduling scheme for wireless sensor networks. It uses time trees for sending data from the sensor node to the base station. For an energy efficient operation of the sensor networks in a distributed manner, time trees are built in order to reduce the collision probability and to minimize the total energy required to send data to the base station. A time tree is a data gathering tree where the base station is the root and each sensor node is either a relaying or a leaf node of the tree. Each tree operates in a different time schedule with possibly different activation rates. Through the simulation, the proposed scheme that uses time trees shows better characteristics toward burst traffic than the previous energy and data arrival rate scheme. PMID:22319270

  16. "This Site Is Blocked": K-12 Teachers and the Challenge of Accessing Peer-to-Peer Networks for Education

    ERIC Educational Resources Information Center

    Ching, Cynthia Carter; Hursh, Anthony W.

    2010-01-01

    This article examines a little-discussed phenomenon in the study of both peer-to-peer collaborative networks and teaching with technology: that of teachers caught in the middle between open public networks as teaching resources and highly restrictive school policies regarding internet content and online access. Based on their experiences as…

  17. The theory research of multi-user quantum access network with Measurement Device Independent quantum key distribution

    NASA Astrophysics Data System (ADS)

    Ji, Yi-Ming; Li, Yun-Xia; Shi, Lei; Meng, Wen; Cui, Shu-Min; Xu, Zhen-Yu

    2015-10-01

    Quantum access network can't guarantee the absolute security of multi-user detector and eavesdropper can get access to key information through time-shift attack and other ways. Measurement-device-independent quantum key distribution is immune from all the detection attacks, and accomplishes the safe sharing of quantum key. In this paper, that Measurement-device-independent quantum key distribution is used in the application of multi-user quantum access to the network is on the research. By adopting time-division multiplexing technology to achieve the sharing of multiuser detector, the system structure is simplified and the security of quantum key sharing is acquired.

  18. Optical access network using centralized light source, single-mode fiber + broad wavelength window multimode fiber

    NASA Astrophysics Data System (ADS)

    Yam, Scott S.-H.; Kim, Jaedon; Gutierrez, David; Achten, Frank

    2006-08-01

    Access networks based on a single-mode fiber (SMF) using a centralized light source (CLS) have attracted much attention recently due to their wavelength management flexibility and potential for cost reduction at customers' premises. Future networks, in addition, are likely to contain segments of multimode fiber (MMF), whose core dimension is relatively large in comparison with its single-mode counterpart, substantially reducing fiber alignment constraints and the subsequent network construction and installation cost. In this study, a CLS-based passive optical network (PON) is proposed, which will use a new generation of high-performance MMF optimized for a broad wavelength transmission window spanning from 1300to1550 nm, with a bandwidth distance product (BDP) of 40 Gbit/s-km. The proposed architecture is implemented in a test bed, and its performance is verified by bit error ratio (BER) measurement. Results show that we can implement high-performance CLS-based PONs containing both an SMF and an MMF infrastructure, simultaneously.

  19. Analyzing the effect of routing protocols on media access control protocols in radio networks

    SciTech Connect

    Barrett, C. L.; Drozda, M.; Marathe, A.; Marathe, M. V.

    2002-01-01

    We study the effect of routing protocols on the performance of media access control (MAC) protocols in wireless radio networks. Three well known MAC protocols: 802.11, CSMA, and MACA are considered. Similarly three recently proposed routing protocols: AODV, DSR and LAR scheme 1 are considered. The experimental analysis was carried out using GloMoSim: a tool for simulating wireless networks. The main focus of our experiments was to study how the routing protocols affect the performance of the MAC protocols when the underlying network and traffic parameters are varied. The performance of the protocols was measured w.r.t. five important parameters: (i) number of received packets, (ii) average latency of each packet, (iii) throughput (iv) long term fairness and (v) number of control packets at the MAC layer level. Our results show that combinations of routing and MAC protocols yield varying performance under varying network topology and traffic situations. The result has an important implication; no combination of routing protocol and MAC protocol is the best over all situations. Also, the performance analysis of protocols at a given level in the protocol stack needs to be studied not locally in isolation but as a part of the complete protocol stack. A novel aspect of our work is the use of statistical technique, ANOVA (Analysis of Variance) to characterize the effect of routing protocols on MAC protocols. This technique is of independent interest and can be utilized in several other simulation and empirical studies.

  20. The dynamics of socio-connective trust within support networks accessed by informal caregivers.

    PubMed

    Ray, Robin A; Street, Annette F

    2011-03-01

    This article introduces the concept of socio-connective trust, the synapse between the social structures and processes that underpin relationships in supportive care networks. Data from an ethnographic case study of 18 informal caregivers providing in-home care for people with life-limiting illness were analysed drawing on theoretical concepts from the work of Giddens and writings on social capital, as well as the construction of trust in the caregiving literature. While conceptions of trust were found to contribute to understanding supportive care relationships, they did not account for the dynamic nature of the availability and use of support networks. Instead, informal caregivers undertook ongoing reflexive negotiation of relationship boundaries in response to their own conception of the current situation and their perception of trust in their relationships with the various members of the support network. The concept of socio-connective trust describes the movement and flow of the flexible bonds that influence relationships among care networks and determine the type and range of support accessed by informal caregivers. Understanding the complexities of socio-connective trust in caregiving relationships will assist health and social care workers to mobilize relevant resources to support informal caregivers.

  1. Nonadditivity of quantum and classical capacities for entanglement breaking multiple-access channels and the butterfly network

    SciTech Connect

    Grudka, Andrzej; Horodecki, Pawel

    2010-06-15

    We analyze quantum network primitives which are entanglement breaking. We show superadditivity of quantum and classical capacity regions for quantum multiple-access channels and the quantum butterfly network. Since the effects are especially visible at high noise they suggest that quantum information effects may be particularly helpful in the case of the networks with occasional high noise rates. The present effects provide a qualitative borderline between superadditivities of bipartite and multipartite systems.

  2. Secret Shoppers Find Access To Providers And Network Accuracy Lacking For Those In Marketplace And Commercial Plans.

    PubMed

    Haeder, Simon F; Weimer, David L; Mukamel, Dana B

    2016-07-01

    The adequacy of provider networks for plans sold through insurance Marketplaces established under the Affordable Care Act has received much scrutiny recently. Various studies have established that networks are generally narrow. To learn more about network adequacy and access to care, we investigated two questions. First, no matter the nominal size of a network, can patients gain access to primary care services from providers of their choice in a timely manner? Second, how does access compare to plans sold outside insurance Marketplaces? We conducted a "secret shopper" survey of 743 primary care providers from five of California's nineteen insurance Marketplace pricing regions in the summer of 2015. Our findings indicate that obtaining access to primary care providers was generally equally challenging both inside and outside insurance Marketplaces. In less than 30 percent of cases were consumers able to schedule an appointment with an initially selected physician provider. Information about provider networks was often inaccurate. Problems accessing services for patients with acute conditions were particularly troubling. Effectively addressing issues of network adequacy requires more accurate provider information. PMID:27385229

  3. National Health Care: How Can the Federal Government Increase Access to Health Care to United States Citizens? National Debate Topic for High Schools, 1993-94. 103rd Congress, 1st Session/Senate Document 103-2.

    ERIC Educational Resources Information Center

    1993

    In compliance with government regulations, this compilation of materials and bibliographic references has been prepared by the Library of Congress to assist debaters in researching the 1993-94 national debate topic for high schools which deals with access by all U.S. citizens to health care. The compilation which was assembled after a review of a…

  4. A Comparative experimental study of media access protocols for wireless radio networks

    SciTech Connect

    Barrett, C. L.; Drozda, M.; Marathe, M. V.

    2001-05-24

    We conduct a comparative experimental analysis of three well known media access protocols: 802.11, CSMA, and MACA for wireless radio networks. Both fixed and ad-hoc networks are considered. The experimental analysis was carried out using GloMoSim: a tool for simulating wireless networks. The main focus of experiments was to study how (i) the size of the network, (ii) number of open connections, (iii) the spatial location of individual connections, (iv) speed with which individual nodes move and (v) protocols higher up in the protocol stack (e,g. routing layer) affect the performance of the media access sublayer protocols. The performance of the protocols was measured w.r.t. three important parameters: (1) number of received packets, (2) average latency of each packet, and (3) throughput. The following general qualitative conclusions were obtained; some of the conclusions reinforce the earlier claims by other researchers. (1) Although 802.11 performs better than the other two protocols with respect to fairness of transmission, packets dropped, and latency, its performance is found to (i) show a lot of variance with changing input parameters and (ii) the overall performance still leaves a lot of room for improvement. (2) CSMA does not perform too well under the fairness criteria, however, was the best in terms of the latency criteria. (3) MACA also shows fairness problems and has poor performance at high packet injection rates. (4) Protocols in the higher level of the protocol stack affect the MAC layer performance. The main general implications of our work is two folds: (1) No single protocol dominated the other protocols across various measures of efficiency. This motivates the design of a new class of parameterized protocols that adapt to changes in the network connectivity and loads. We refer to these class of protocols as parameterized dynamically adaptive efficient protocols and as a first step suggest key design requirements for such a class of protocols. (2

  5. Do You Lock Your Network Doors? Some Network Management Precautions.

    ERIC Educational Resources Information Center

    Neray, Phil

    1997-01-01

    Discusses security problems and solutions for networked organizations with Internet connections. Topics include access to private networks from electronic mail information; computer viruses; computer software; corporate espionage; firewalls, that is computers that stand between a local network and the Internet; passwords; and physical security.…

  6. Bearer channel control protocol for the dynamic VB5.2 interface in ATM access networks

    NASA Astrophysics Data System (ADS)

    Fragoulopoulos, Stratos K.; Mavrommatis, K. I.; Venieris, Iakovos S.

    1996-12-01

    In the multi-vendor systems, a customer connected to an Access network (AN) must be capable of selecting a specific Service Node (SN) according to the services the SN provides. The multiplicity of technologically varying AN calls for the definition of a standard reference point between the AN and the SN widely known as the VB interface. Two versions are currently offered. The VB5.1 is simpler to implement but is not as flexible as the VB5.2, which supports switched connections. The VB5.2 functionality is closely coupled to the Broadband Bearer Channel Connection Protocol (B-BCCP). The B-BCCP is used for conveying the necessary information for dynamic resource allocation, traffic policing and routing in the AN as well as for information exchange concerning the status of the AN before a new call is established by the SN. By relying on such a protocol for the exchange of information instead of intercepting and interpreting signalling messages in the AN, the architecture of the AN is simplified because the functionality related to processing is not duplicated. In this paper a prominent B- BCCP candidate is defined, called the Service node Access network Interaction Protocol.

  7. Connectivity and conditional models of access and abundance of species in stream networks.

    PubMed

    Chelgren, Nathan D; Dunham, Jason B

    2015-07-01

    Barriers to passage of aquatic organisms at stream road crossings are a major cause of habitat fragmentation in stream networks. Accordingly, large investments have been made to restore passage at these crossings, but often without estimation of population-level benefits. Here, we describe a broad-scale approach to quantifying the effectiveness of passage restoration in terms interpretable at population levels, namely numbers of fish and length of stream gained through restoration, by sampling abundance in a study design that accounts for variable biogeographic species pools, variable stream and barrier configurations, and variable probabilities of capture and detectability for multiple species. We modified an existing zero-inflated negative-binomial model to estimate the probability of site access, abundance conditional on access, and capture probability of individual fish. Therein, we modeled probability of access as a function of gradient, stream road-crossing type, and downstream access by fish simultaneously with a predictive model for abundance at sites accessible to fish. Results indicated that replacement of barriers with new crossing designs intended to allow for greater movement was associated with dramatically higher probability of access for all fishes, including migratory Pacific salmon, trout, sculpin, and lamprey. Conversely, existing non-replaced crossings negatively impacted fish distributions. Assuming no downstream constraints on access, we estimated the potential length of stream restored by the program ranged between 7.33 (lamprey) and 15.28 km (small coastal cutthroat and rainbow trout). These contributions represented a fraction of the total length available upstream (187 km) of replaced crossings. When limited ranges of species were considered, the estimated contributions of culvert replacement were reduced (1.65-km range, for longnose dace to 12.31 km for small coastal cutthroat and rainbow trout). Numbers of fish contributed ranged from

  8. Connectivity and conditional models of access and abundance of species in stream networks.

    PubMed

    Chelgren, Nathan D; Dunham, Jason B

    2015-07-01

    Barriers to passage of aquatic organisms at stream road crossings are a major cause of habitat fragmentation in stream networks. Accordingly, large investments have been made to restore passage at these crossings, but often without estimation of population-level benefits. Here, we describe a broad-scale approach to quantifying the effectiveness of passage restoration in terms interpretable at population levels, namely numbers of fish and length of stream gained through restoration, by sampling abundance in a study design that accounts for variable biogeographic species pools, variable stream and barrier configurations, and variable probabilities of capture and detectability for multiple species. We modified an existing zero-inflated negative-binomial model to estimate the probability of site access, abundance conditional on access, and capture probability of individual fish. Therein, we modeled probability of access as a function of gradient, stream road-crossing type, and downstream access by fish simultaneously with a predictive model for abundance at sites accessible to fish. Results indicated that replacement of barriers with new crossing designs intended to allow for greater movement was associated with dramatically higher probability of access for all fishes, including migratory Pacific salmon, trout, sculpin, and lamprey. Conversely, existing non-replaced crossings negatively impacted fish distributions. Assuming no downstream constraints on access, we estimated the potential length of stream restored by the program ranged between 7.33 (lamprey) and 15.28 km (small coastal cutthroat and rainbow trout). These contributions represented a fraction of the total length available upstream (187 km) of replaced crossings. When limited ranges of species were considered, the estimated contributions of culvert replacement were reduced (1.65-km range, for longnose dace to 12.31 km for small coastal cutthroat and rainbow trout). Numbers of fish contributed ranged from

  9. Breaking Free with Wireless Networks.

    ERIC Educational Resources Information Center

    Fleischman, John

    2002-01-01

    Discusses wireless local area networks (LANs) which typically consist of laptop computers that connect to fixed access points via infrared or radio signals. Topics include wide area networks; personal area networks; problems, including limitations of available bandwidth, interference, and security concerns; use in education; interoperability;…

  10. Security of social network credentials for accessing course portal: Users' experience

    NASA Astrophysics Data System (ADS)

    Katuk, Norliza; Fong, Choo Sok; Chun, Koo Lee

    2015-12-01

    Social login (SL) has recently emerged as a solution for single sign-on (SSO) within the web and mobile environments. It allows users to use their existing social network credentials (SNC) to login to third party web applications without the need to create a new identity in the intended applications' database. Although it has been used by many web application providers, its' applicability in accessing learning materials is not yet fully investigated. Hence, this research aims to explore users' (i.e., instructors' and students') perception and experience on the security of SL for accessing learning contents. A course portal was developed for students at a higher learning institution and it provides two types of user authentications (i) traditional user authentication, and (ii) SL facility. Users comprised instructors and students evaluated the login facility of the course portal through a controlled lab experimental study following the within-subject design. The participants provided their feedback in terms of the security of SL for accessing learning contents. The study revealed that users preferred to use SL over the traditional authentication, however, they concerned on the security of SL and their privacy.

  11. Groundwater Information Network: enabling online access and analysis of Canadian groundwater information

    NASA Astrophysics Data System (ADS)

    Brodaric, B.; Sharpe, D.; Boisvert, E.

    2009-05-01

    A cornerstone of effective groundwater resource management is access to available groundwater information and tools for analysis, modeling, and eventually decision-making. In Canada, information access is inhibited by the heterogeneous nature of groundwater information, which is collected and maintained by many agencies using different digital structures and contents, and by varying online availability. To overcome these issues, a collaboration of federal and provincial agencies has developed the Groundwater Information Network (GIN, http://gw-info.net). In its first phase, GIN provides a single online data pipeline to the water-well databases hosted by six provincial agencies (British Columbia, Alberta, Manitoba, Ontario, Quebec and Nova Scotia) and to some key aquifer information hosted by Natural Resources Canada. GIN also provides two online portals that can be used to view, download and analyse the information. At the core of GIN is an online mediator that distributes requests for information to the host databases, and translates the replies into a common format (Groundwater MarkUp Language). This allows the portals to treat the distributed information as a single virtual online repository, one with consistent links back to the original databases. Discussed will be the GIN system, including its architecture, functionality, and portals, as well as its overall role as a point of access to some Canadian groundwater information as well as to related web-mapping and analysis tools.

  12. All-optical multiplexing schemes for multiple access networks based on wavelet packet filter banks

    NASA Astrophysics Data System (ADS)

    Cincotti, Gabriella; Svaluto Moreolo, Michela; Neri, Alessandro

    2004-08-01

    All optical architectures for Wavelet Packet Division Multiplexing (WPDM) are presented, that can be used in multiple access networks to increase the number of simultaneous users. Wavelet waveform coding spreads data signals both in time and frequency domains, with a large capacity improvement with respect to standard Optical-Code Division Multiple Access (O-CDMA) systems. In addition, the orthogonal property of the wavelet atoms ensures low InterSymbol Interference (ISI) and Multiple Access Interference (MAI) noises. To exploit the large bandwidth capacity of optical fibres, the Optical-Electrical-Optical (O-E-O) conversion is completely avoided, and we designed an all optical system that realizes the WPDM fully in the optical domain. A single Planar Lightwave Circuit (PLC) device multiplies/demultiplies N different users and a diffractive or an integrated optical device performs the waveform coding/decoding. The Wavelet Packet (WP) encoder/decoder is realized as a tree of lattice-form delay-line filters, and can be integrated on a single device along with the optical waveform modulator, resulting in a compact planar optical system. In addition, we show that different choices of WP encoders/decoders are possible to further enhance the system performances.

  13. Adaptive MAC-layer protocol for multiservice digital access via tree and branch communication networks

    NASA Astrophysics Data System (ADS)

    Kotikalapudi, Sriram; Li, Chia-Chang; Magill, Peter D.; Whitaker, Norman A.; Dail, James E.; Dajer, Miguel A.; Siller, Curtis A., Jr.

    1995-11-01

    Described here is an adaptive MAC-layer protocol that supports multiservice (STM and ATM) applications in the context of subscriber access to tree and branch (e.g., fiber-coaxial cable) networks. The protocol adapts to changing demands for a mix of circuit and cell mode applications, and efficiently allocates upstream and downstream bandwidth to a variety of bursty and isochronous traffic sources. In the case of a hybrid fiber-coaxial (HFC) network the protocol resides in customer premises equipment and a common head-end controller. A medium-access control (MAC) processor provides for dividing the time domain for a given digital bitstream into successive frames, each with multiple STM and ATM time slots. Within the STM region of a frame, variable length time slots are allocated to calls (e.g., telephony, video telephony) requiring different amounts of bandwidth. A contention access signaling channel is also provided in this region for call control and set-up requests. Within the ATM region fixed-length time slots accommodate one individual ATM cell. These ATM time slots may be reserved for a user for the duration of a call or burst of successive ATM cells, or shared via a contention process. At least one contention time slot is available for signaling messages related to ATM call control and set-up requests. Further, the fixed-length ATM time slots may be reserved by a user for the duration of a call, or shared through a contention process. This paper describes the MAC-layer protocol, its relation to circuit- and ATM- amenable applications, and its performance with respect to signaling throughput and latency, and bandwidth efficiency for several service scenarios.

  14. California hospital networks are narrower in Marketplace than in commercial plans, but access and quality are similar.

    PubMed

    Haeder, Simon F; Weimer, David L; Mukamel, Dana B

    2015-05-01

    Do insurance plans offered through the Marketplace implemented by the State of California under the Affordable Care Act restrict consumers' access to hospitals relative to plans offered on the commercial market? And are the hospitals included in Marketplace networks of lower quality compared to those included in the commercial plans? To answer these questions, we analyzed differences in hospital networks across similar plan types offered both in the Marketplace and commercially, by region and insurer. We found that the common belief that Marketplace plans have narrower networks than their commercial counterparts appears empirically valid. However, there does not appear to be a substantive difference in geographic access as measured by the percentage of people residing in at least one hospital market area. More surprisingly, depending on the measure of hospital quality employed, the Marketplace plans have networks with comparable or even higher average quality than the networks of their commercial counterparts.

  15. Permanent Access to the Seafloor Through Ocean Networks Canada - Key Discoveries From Nine Years of Data

    NASA Astrophysics Data System (ADS)

    Scherwath, Martin; Dewey, Richard; Heesemann, Martin; Thomsen, Laurenz; Purser, Autun; Roemer, Miriam; Xu, Guangyu

    2015-04-01

    Ocean Networks Canada operates ocean observatories and hosts data from the Canadian Pacific, Arctic and recently the Atlantic Ocean. The two prominent observatories are VENUS (Victoria Experimental Network Under the Sea), online since 2006, inshore from Vancouver Island in the Salish Sea, and NEPTUNE (North East Pacific Time-series Underwater Networked Experiments), offshore at the northern Cascadia margin across the Juan de Fuca Plate, online since 2009. Over 250 Terabytes of data have been collected and are openly and freely accessible. Geoscientific research has made use of these high-resolution permanent time series and started to quantify ocean and seafloor dynamics. For example, upward-looking echo-sounders quantify vertical migration of euphausiids (e.g. krill) in the water column, showing additional environment- and growth-related influence to the expected light intensity-related diel migration pattern; or camera observations quantify in-situ the speed of bacterial mat withering, clam movements and local anoxic region distribution changes; or rotating sonars show unprecedented long-term stability observations of a hydrothermal vent system and the sudden changes after a local earthquake, or at a gas hydrate field sonar data detect gas venting that has an amazingly specific tidal pressure correlation which hints at internal sediment processes in relation to gas hydrate dissociation; or a regional array of bottom pressure recorders has detected five major tsunami events which help fine-tune tsunami models for better hazard preparedness.

  16. 47 CFR 27.16 - Network access requirements for Block C in the 746-757 and 776-787 MHz bands.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Network access requirements for Block C in the... § 27.16 Network access requirements for Block C in the 746-757 and 776-787 MHz bands. (a) Applicability... the devices and applications of their choice on the licensee's C Block network, except: (1) Insofar...

  17. Energy-efficient boarder node medium access control protocol for wireless sensor networks.

    PubMed

    Razaque, Abdul; Elleithy, Khaled M

    2014-03-12

    This paper introduces the design, implementation, and performance analysis of the scalable and mobility-aware hybrid protocol named boarder node medium access control (BN-MAC) for wireless sensor networks (WSNs), which leverages the characteristics of scheduled and contention-based MAC protocols. Like contention-based MAC protocols, BN-MAC achieves high channel utilization, network adaptability under heavy traffic and mobility, and low latency and overhead. Like schedule-based MAC protocols, BN-MAC reduces idle listening time, emissions, and collision handling at low cost at one-hop neighbor nodes and achieves high channel utilization under heavy network loads. BN-MAC is particularly designed for region-wise WSNs. Each region is controlled by a boarder node (BN), which is of paramount importance. The BN coordinates with the remaining nodes within and beyond the region. Unlike other hybrid MAC protocols, BN-MAC incorporates three promising models that further reduce the energy consumption, idle listening time, overhearing, and congestion to improve the throughput and reduce the latency. One of the models used with BN-MAC is automatic active and sleep (AAS), which reduces the ideal listening time. When nodes finish their monitoring process, AAS lets them automatically go into the sleep state to avoid the idle listening state. Another model used in BN-MAC is the intelligent decision-making (IDM) model, which helps the nodes sense the nature of the environment. Based on the nature of the environment, the nodes decide whether to use the active or passive mode. This decision power of the nodes further reduces energy consumption because the nodes turn off the radio of the transceiver in the passive mode. The third model is the least-distance smart neighboring search (LDSNS), which determines the shortest efficient path to the one-hop neighbor and also provides cross-layering support to handle the mobility of the nodes. The BN-MAC also incorporates a semi

  18. Energy-Efficient Boarder Node Medium Access Control Protocol for Wireless Sensor Networks

    PubMed Central

    Razaque, Abdul; Elleithy, Khaled M.

    2014-01-01

    This paper introduces the design, implementation, and performance analysis of the scalable and mobility-aware hybrid protocol named boarder node medium access control (BN-MAC) for wireless sensor networks (WSNs), which leverages the characteristics of scheduled and contention-based MAC protocols. Like contention-based MAC protocols, BN-MAC achieves high channel utilization, network adaptability under heavy traffic and mobility, and low latency and overhead. Like schedule-based MAC protocols, BN-MAC reduces idle listening time, emissions, and collision handling at low cost at one-hop neighbor nodes and achieves high channel utilization under heavy network loads. BN-MAC is particularly designed for region-wise WSNs. Each region is controlled by a boarder node (BN), which is of paramount importance. The BN coordinates with the remaining nodes within and beyond the region. Unlike other hybrid MAC protocols, BN-MAC incorporates three promising models that further reduce the energy consumption, idle listening time, overhearing, and congestion to improve the throughput and reduce the latency. One of the models used with BN-MAC is automatic active and sleep (AAS), which reduces the ideal listening time. When nodes finish their monitoring process, AAS lets them automatically go into the sleep state to avoid the idle listening state. Another model used in BN-MAC is the intelligent decision-making (IDM) model, which helps the nodes sense the nature of the environment. Based on the nature of the environment, the nodes decide whether to use the active or passive mode. This decision power of the nodes further reduces energy consumption because the nodes turn off the radio of the transceiver in the passive mode. The third model is the least-distance smart neighboring search (LDSNS), which determines the shortest efficient path to the one-hop neighbor and also provides cross-layering support to handle the mobility of the nodes. The BN-MAC also incorporates a semi

  19. Networking the Light Fantastic--CD-ROMs on LANs.

    ERIC Educational Resources Information Center

    Kittle, Paul W.

    1992-01-01

    Describes the development of a local area network (LAN) at Loma Linda University that allows remote access for both IBM and Macintosh microcomputers to CD-ROMs. Topics discussed include types of networks; fiber optic technology; networking CD-ROM drives; remote access; modems; CD-ROM databases; memory management; interface software; and future…

  20. An open-access modeled passenger flow matrix for the global air network in 2010.

    PubMed

    Huang, Zhuojie; Wu, Xiao; Garcia, Andres J; Fik, Timothy J; Tatem, Andrew J

    2013-01-01

    The expanding global air network provides rapid and wide-reaching connections accelerating both domestic and international travel. To understand human movement patterns on the network and their socioeconomic, environmental and epidemiological implications, information on passenger flow is required. However, comprehensive data on global passenger flow remain difficult and expensive to obtain, prompting researchers to rely on scheduled flight seat capacity data or simple models of flow. This study describes the construction of an open-access modeled passenger flow matrix for all airports with a host city-population of more than 100,000 and within two transfers of air travel from various publicly available air travel datasets. Data on network characteristics, city population, and local area GDP amongst others are utilized as covariates in a spatial interaction framework to predict the air transportation flows between airports. Training datasets based on information from various transportation organizations in the United States, Canada and the European Union were assembled. A log-linear model controlling the random effects on origin, destination and the airport hierarchy was then built to predict passenger flows on the network, and compared to the results produced using previously published models. Validation analyses showed that the model presented here produced improved predictive power and accuracy compared to previously published models, yielding the highest successful prediction rate at the global scale. Based on this model, passenger flows between 1,491 airports on 644,406 unique routes were estimated in the prediction dataset. The airport node characteristics and estimated passenger flows are freely available as part of the Vector-Borne Disease Airline Importation Risk (VBD-Air) project at: www.vbd-air.com/data.

  1. Experimental Investigation on Transmission Control Protocol Throughput Behavior in Optical Fiber Access Networks

    NASA Astrophysics Data System (ADS)

    Tego, Edion; Matera, Francesco; del Buono, Donato

    2016-03-01

    This article describes an experimental investigation on the behavior of transmission control protocol in throughput measurements to be used in the verification of the service-level agreement between the Internet service provider and user in terms of line capacity for ultra-broadband access networks typical of fiber-to-the-x architectures. It is experimentally shown different conditions in high bandwidth-delay product links where the estimation of the line capacity based on a single transmission control protocol session results are unreliable. Simple equations reported in this work, and experimentally verified, point out the conditions in terms of packet loss, time delay, and line capacity, that allow consideration of the reliability of the measurement carried out with a single transmission control protocol session test by adopting a suitable measurement time duration.

  2. Experimental demonstration of cascaded AWG access network featuring bi-directional transmission and polarization multiplexing.

    PubMed

    Tsalamanis, Ioannis; Rochat, Etienne; Walker, Stuart; Parker, Michael; Holburn, D

    2004-03-01

    We present the first experimental demonstration of a bidirectional cascaded arrayed-waveguide grating (AWG) access network combining one NxN AWG in the central office with multiple 1xN AWG's at the distribution points, such as to individually address N(2) users with only N wavelengths. Downstream and upstream data share the same optical path. BER curves were measured using 2.5Gb/s data stream in each direction, and error free transmission achieved for downstream and upstream, with only 0.3dB power penalty for simultaneous transmission. The addition of two orthogonal polarization-multiplexed channels per wavelength doubled the number of possible end users. Error free transmission was achieved with simultaneous upstream and downstream transmission of a composite signal featuring eight 2.5Gb/s channels (2 polarizations x 4 wavelengths). PMID:19474883

  3. An Analysis of Medication Adherence of Sooner Health Access Network SoonerCare Choice Patients.

    PubMed

    Davis, Nicholas A; Kendrick, David C

    2014-01-01

    Medication adherence is a desirable but rarely available metric in patient care, providing key insights into patient behavior that has a direct effect on a patient's health. In this research, we determine the medication adherence characteristics of over 46,000 patients enrolled in the Sooner Health Access Network (HAN), based on Medicaid claims data from the Oklahoma Health Care Authority. We introduce a new measure called Specific Medication PDC (smPDC), based on the popular Proportion of Days Covered (PDC) method, using the last fill date for the end date of the measurement duration. The smPDC method is demonstrated by calculating medication adherence across the eligible patient population, for relevant subpopulations over a two-year period spanning 2012 - 2013. We leverage a clinical analytics platform to disseminate adherence measurements to providers. Aggregate results demonstrate that the smPDC method is relevant and indicates potential opportunities for health improvement for certain population segments. PMID:25954350

  4. An Analysis of Medication Adherence of Sooner Health Access Network SoonerCare Choice Patients.

    PubMed

    Davis, Nicholas A; Kendrick, David C

    2014-01-01

    Medication adherence is a desirable but rarely available metric in patient care, providing key insights into patient behavior that has a direct effect on a patient's health. In this research, we determine the medication adherence characteristics of over 46,000 patients enrolled in the Sooner Health Access Network (HAN), based on Medicaid claims data from the Oklahoma Health Care Authority. We introduce a new measure called Specific Medication PDC (smPDC), based on the popular Proportion of Days Covered (PDC) method, using the last fill date for the end date of the measurement duration. The smPDC method is demonstrated by calculating medication adherence across the eligible patient population, for relevant subpopulations over a two-year period spanning 2012 - 2013. We leverage a clinical analytics platform to disseminate adherence measurements to providers. Aggregate results demonstrate that the smPDC method is relevant and indicates potential opportunities for health improvement for certain population segments.

  5. A nomadic access mechanism for enabling dynamic video surveillance over IEEE 802.15.4 networks

    NASA Astrophysics Data System (ADS)

    Garcia-Sanchez, Felipe; Garcia-Sanchez, Antonio-Javier; Losilla, Fernando; Garcia-Haro, Joan

    2010-12-01

    IEEE 802.15.4 networking technology is designed to be the common standard for integrating WSN applications in heterogeneous environments. However, applications considering mobile nodes along with strict temporal requirements, such as those required for video transmission, are an unexplored field for this technology. These applications involve different challenges and issues that the direct employment of the IEEE 802.15.4 standard does not resolve. Therefore, in this paper a cross-layer mechanism consisting of application and medium access arbitration is presented, enabling the efficient connection and operation of mobile nodes together with the transmission of video flows. The proposed mechanism is evaluated via simulation and its feasibility checked by means of a first prototype. The study of power consumption is also taken into account and so are the quality of service parameters and the human quality perception of the received video stream. The results obtained are presented and further discussed.

  6. Optical Shared Memory Computing and Multiple Access Protocols for Photonic Networks

    NASA Astrophysics Data System (ADS)

    Li, Kuang-Yu.

    In this research we investigate potential applications of optics in massively parallel computer systems, especially focusing on design issues in three-dimensional optical data storage and free-space photonic networks. An optical implementation of a shared memory uses a single photorefractive crystal and can realize the set of memory modules in a digital shared memory computer. A complete instruction set consists of R sc EAD, W sc RITE, S sc ELECTIVE E sc RASE, and R sc EFRESH, which can be applied to any memory module independent of (and in parallel with) instructions to the other memory modules. In addition, a memory module can execute a sequence of R sc EAD operations simultaneously with the execution of a W sc RITE operation to accommodate differences in optical recording and readout times common to optical volume storage media. An experimental shared memory system is demonstrated and its projected performance is analyzed. A multiplexing technique is presented to significantly reduce both grating- and beam-degeneracy crosstalk in volume holographic systems, by incorporating space, angle, and wavelength as the multiplexing parameters. In this approach, each hologram, which results from the interference between a single input node and an object array, partially overlaps with the other holograms in its neighborhood. This technique can offer improved interconnection density, optical throughput, signal fidelity, and space-bandwidth product utilization. Design principles and numerical simulation results are presented. A free-space photonic cellular hypercube parallel computer, with emphasis on the design of a collisionless multiple access protocol, is presented. This design incorporates wavelength-, space-, and time-multiplexing to achieve multiple access, wavelength reuse, dense connectivity, collisionless communications, and a simple control mechanism. Analytic models based on semi-Markov processes are employed to analyze this protocol. The performance of the

  7. Decentralized Opportunistic Spectrum Resources Access Model and Algorithm toward Cooperative Ad-Hoc Networks.

    PubMed

    Liu, Ming; Xu, Yang; Mohammed, Abdul-Wahid

    2016-01-01

    Limited communication resources have gradually become a critical factor toward efficiency of decentralized large scale multi-agent coordination when both system scales up and tasks become more complex. In current researches, due to the agent's limited communication and observational capability, an agent in a decentralized setting can only choose a part of channels to access, but cannot perceive or share global information. Each agent's cooperative decision is based on the partial observation of the system state, and as such, uncertainty in the communication network is unavoidable. In this situation, it is a major challenge working out cooperative decision-making under uncertainty with only a partial observation of the environment. In this paper, we propose a decentralized approach that allows agents cooperatively search and independently choose channels. The key to our design is to build an up-to-date observation for each agent's view so that a local decision model is achievable in a large scale team coordination. We simplify the Dec-POMDP model problem, and each agent can jointly work out its communication policy in order to improve its local decision utilities for the choice of communication resources. Finally, we discuss an implicate resource competition game, and show that, there exists an approximate resources access tradeoff balance between agents. Based on this discovery, the tradeoff between real-time decision-making and the efficiency of cooperation using these channels can be well improved. PMID:26727504

  8. FunRich: An open access standalone functional enrichment and interaction network analysis tool.

    PubMed

    Pathan, Mohashin; Keerthikumar, Shivakumar; Ang, Ching-Seng; Gangoda, Lahiru; Quek, Camelia Y J; Williamson, Nicholas A; Mouradov, Dmitri; Sieber, Oliver M; Simpson, Richard J; Salim, Agus; Bacic, Antony; Hill, Andrew F; Stroud, David A; Ryan, Michael T; Agbinya, Johnson I; Mariadason, John M; Burgess, Antony W; Mathivanan, Suresh

    2015-08-01

    As high-throughput techniques including proteomics become more accessible to individual laboratories, there is an urgent need for a user-friendly bioinformatics analysis system. Here, we describe FunRich, an open access, standalone functional enrichment and network analysis tool. FunRich is designed to be used by biologists with minimal or no support from computational and database experts. Using FunRich, users can perform functional enrichment analysis on background databases that are integrated from heterogeneous genomic and proteomic resources (>1.5 million annotations). Besides default human specific FunRich database, users can download data from the UniProt database, which currently supports 20 different taxonomies against which enrichment analysis can be performed. Moreover, the users can build their own custom databases and perform the enrichment analysis irrespective of organism. In addition to proteomics datasets, the custom database allows for the tool to be used for genomics, lipidomics and metabolomics datasets. Thus, FunRich allows for complete database customization and thereby permits for the tool to be exploited as a skeleton for enrichment analysis irrespective of the data type or organism used. FunRich (http://www.funrich.org) is user-friendly and provides graphical representation (Venn, pie charts, bar graphs, column, heatmap and doughnuts) of the data with customizable font, scale and color (publication quality).

  9. Decentralized Opportunistic Spectrum Resources Access Model and Algorithm toward Cooperative Ad-Hoc Networks

    PubMed Central

    Liu, Ming; Xu, Yang; Mohammed, Abdul-Wahid

    2016-01-01

    Limited communication resources have gradually become a critical factor toward efficiency of decentralized large scale multi-agent coordination when both system scales up and tasks become more complex. In current researches, due to the agent’s limited communication and observational capability, an agent in a decentralized setting can only choose a part of channels to access, but cannot perceive or share global information. Each agent’s cooperative decision is based on the partial observation of the system state, and as such, uncertainty in the communication network is unavoidable. In this situation, it is a major challenge working out cooperative decision-making under uncertainty with only a partial observation of the environment. In this paper, we propose a decentralized approach that allows agents cooperatively search and independently choose channels. The key to our design is to build an up-to-date observation for each agent’s view so that a local decision model is achievable in a large scale team coordination. We simplify the Dec-POMDP model problem, and each agent can jointly work out its communication policy in order to improve its local decision utilities for the choice of communication resources. Finally, we discuss an implicate resource competition game, and show that, there exists an approximate resources access tradeoff balance between agents. Based on this discovery, the tradeoff between real-time decision-making and the efficiency of cooperation using these channels can be well improved. PMID:26727504

  10. Decentralized Opportunistic Spectrum Resources Access Model and Algorithm toward Cooperative Ad-Hoc Networks.

    PubMed

    Liu, Ming; Xu, Yang; Mohammed, Abdul-Wahid

    2016-01-01

    Limited communication resources have gradually become a critical factor toward efficiency of decentralized large scale multi-agent coordination when both system scales up and tasks become more complex. In current researches, due to the agent's limited communication and observational capability, an agent in a decentralized setting can only choose a part of channels to access, but cannot perceive or share global information. Each agent's cooperative decision is based on the partial observation of the system state, and as such, uncertainty in the communication network is unavoidable. In this situation, it is a major challenge working out cooperative decision-making under uncertainty with only a partial observation of the environment. In this paper, we propose a decentralized approach that allows agents cooperatively search and independently choose channels. The key to our design is to build an up-to-date observation for each agent's view so that a local decision model is achievable in a large scale team coordination. We simplify the Dec-POMDP model problem, and each agent can jointly work out its communication policy in order to improve its local decision utilities for the choice of communication resources. Finally, we discuss an implicate resource competition game, and show that, there exists an approximate resources access tradeoff balance between agents. Based on this discovery, the tradeoff between real-time decision-making and the efficiency of cooperation using these channels can be well improved.

  11. Formats and Network Protocols for Browser Access to 2D Raster Data

    NASA Astrophysics Data System (ADS)

    Plesea, L.

    2015-12-01

    Tiled web maps in browsers are a major success story, forming the foundation of many current web applications. Enabling tiled data access is the next logical step, and is likely to meet with similar success. Many ad-hoc approaches have already started to appear, and something similar is explored within the Open Geospatial Consortium. One of the main obstacles in making browser data access a reality is the lack of a well-known data format. This obstacle also represents an opportunity to analyze the requirements and possible candidates, applying lessons learned from web tiled image services and protocols. Similar to the image counterpart, a web tile raster data format needs to have good intrinsic compression and be able to handle high byte count data types including floating point. An overview of a possible solution to the format problem, a 2D data raster compression algorithm called Limited Error Raster Compression (LERC) will be presented. In addition to the format, best practices for high request rate HTTP services also need to be followed. In particular, content delivery network (CDN) caching suitability needs to be part of any design, not an after-thought. Last but not least, HTML 5 browsers will certainly be part of any solution since they provide improved access to binary data, as well as more powerful ways to view and interact with the data in the browser. In a simple but relevant application, digital elevation model (DEM) raster data is served as LERC compressed data tiles which are used to generate terrain by a HTML5 scene viewer.

  12. A Spectrum Access Based on Quality of Service (QoS) in Cognitive Radio Networks.

    PubMed

    Zhai, Linbo; Wang, Hua; Gao, Chuangen

    2016-01-01

    The quality of service (QoS) is important issue for cognitive radio networks. In the cognitive radio system, the licensed users, also called primary users (PUs), are authorized to utilize the wireless spectrum, while unlicensed users, also called secondary users (SUs), are not authorized to use the wireless spectrum. SUs access the wireless spectrum opportunistically when the spectrum is idle. While SUs use an idle channel, the instance that PUs come back makes SUs terminate their communications and leave the current channel. Therefore, quality of service (QoS) is difficult to be ensured for SUs. In this paper, we first propose an analysis model to obtain QoS for cognitive radio networks such as blocking probability, completed traffic and termination probability of SUs. When the primary users use the channels frequently, QoS of SUs is difficult to be ensured, especially the termination probability. Then, we propose a channel reservation scheme to improve QoS of SUs. The scheme makes the terminated SUs move to the reserved channels and keep on communications. Simulation results show that our scheme can improve QoS of SUs especially the termination probability with a little cost of blocking probability in dynamic environment. PMID:27171196

  13. A Spectrum Access Based on Quality of Service (QoS) in Cognitive Radio Networks

    PubMed Central

    Zhai, Linbo; Wang, Hua; Gao, Chuangen

    2016-01-01

    The quality of service (QoS) is important issue for cognitive radio networks. In the cognitive radio system, the licensed users, also called primary users (PUs), are authorized to utilize the wireless spectrum, while unlicensed users, also called secondary users (SUs), are not authorized to use the wireless spectrum. SUs access the wireless spectrum opportunistically when the spectrum is idle. While SUs use an idle channel, the instance that PUs come back makes SUs terminate their communications and leave the current channel. Therefore, quality of service (QoS) is difficult to be ensured for SUs. In this paper, we first propose an analysis model to obtain QoS for cognitive radio networks such as blocking probability, completed traffic and termination probability of SUs. When the primary users use the channels frequently, QoS of SUs is difficult to be ensured, especially the termination probability. Then, we propose a channel reservation scheme to improve QoS of SUs. The scheme makes the terminated SUs move to the reserved channels and keep on communications. Simulation results show that our scheme can improve QoS of SUs especially the termination probability with a little cost of blocking probability in dynamic environment. PMID:27171196

  14. Entanglement distribution over quantum code-division multiple-access networks

    NASA Astrophysics Data System (ADS)

    Zhu, Chang-long; Yang, Nan; Liu, Yu-xi; Nori, Franco; Zhang, Jing

    2015-10-01

    We present a method for quantum entanglement distribution over a so-called code-division multiple-access network, in which two pairs of users share the same quantum channel to transmit information. The main idea of this method is to use different broadband chaotic phase shifts, generated by electro-optic modulators and chaotic Colpitts circuits, to encode the information-bearing quantum signals coming from different users and then recover the masked quantum signals at the receiver side by imposing opposite chaotic phase shifts. The chaotic phase shifts given to different pairs of users are almost uncorrelated due to the randomness of chaos and thus the quantum signals from different pair of users can be distinguished even when they are sent via the same quantum channel. It is shown that two maximally entangled states can be generated between two pairs of users by our method mediated by bright coherent lights, which can be more easily implemented in experiments compared with single-photon lights. Our method is robust under the channel noises if only the decay rates of the information-bearing fields induced by the channel noises are not quite high. Our study opens up new perspectives for addressing and transmitting quantum information in future quantum networks.

  15. Satellite range delay simulator for a matrix-switched time division multiple-access network simulator

    NASA Technical Reports Server (NTRS)

    Nagy, Lawrence A.

    1989-01-01

    The Systems Integration, Test, and Evaluation (SITE) facility at NASA Lewis Research Center is presently configured as a satellite-switched time division multiple access (SS-TDMA) network simulator. The purpose of SITE is to demonstrate and evaluate advanced communication satellite technologies, presently embodied by POC components developed under NASA contracts in addition to other hardware, such as ground terminals, designed and built in-house at NASA Lewis. Each ground terminal in a satellite communications system will experience a different aspect of the satellite's motion due mainly to daily tidal effects and station keeping, hence a different duration and rate of variation in the range delay. As a result of this and other effects such as local oscillator instability, each ground terminal must constantly adjust its transmit burst timing so that data bursts from separate ground terminals arrive at the satellite in their assigned time slots, preventing overlap and keeping the system in synchronism. On the receiving end, ground terminals must synchronize their local clocks using reference transmissions received through the satellite link. A feature of the SITE facility is its capability to simulate the varying propagation delays and associated Doppler frequency shifts that the ground terminals in the network have to cope with. Delay is achieved by means of two NASA Lewis designed and built range delay simulator (RDS) systems, each independently controlled locally with front panel switches or remotely by an experiment control and monitor (EC/M) computer.

  16. Adaptive Code Division Multiple Access Protocol for Wireless Network-on-Chip Architectures

    NASA Astrophysics Data System (ADS)

    Vijayakumaran, Vineeth

    Massive levels of integration following Moore's Law ushered in a paradigm shift in the way on-chip interconnections were designed. With higher and higher number of cores on the same die traditional bus based interconnections are no longer a scalable communication infrastructure. On-chip networks were proposed enabled a scalable plug-and-play mechanism for interconnecting hundreds of cores on the same chip. Wired interconnects between the cores in a traditional Network-on-Chip (NoC) system, becomes a bottleneck with increase in the number of cores thereby increasing the latency and energy to transmit signals over them. Hence, there has been many alternative emerging interconnect technologies proposed, namely, 3D, photonic and multi-band RF interconnects. Although they provide better connectivity, higher speed and higher bandwidth compared to wired interconnects; they also face challenges with heat dissipation and manufacturing difficulties. On-chip wireless interconnects is one other alternative proposed which doesn't need physical interconnection layout as data travels over the wireless medium. They are integrated into a hybrid NOC architecture consisting of both wired and wireless links, which provides higher bandwidth, lower latency, lesser area overhead and reduced energy dissipation in communication. However, as the bandwidth of the wireless channels is limited, an efficient media access control (MAC) scheme is required to enhance the utilization of the available bandwidth. This thesis proposes using a multiple access mechanism such as Code Division Multiple Access (CDMA) to enable multiple transmitter-receiver pairs to send data over the wireless channel simultaneously. It will be shown that such a hybrid wireless NoC with an efficient CDMA based MAC protocol can significantly increase the performance of the system while lowering the energy dissipation in data transfer. In this work it is shown that the wireless NoC with the proposed CDMA based MAC protocol

  17. Louisiana coastal GIS network: Graphical user interface for access to spatial data

    USGS Publications Warehouse

    Hiland, Matteson; McBride, Randolph A.; Davis, Donald; Braud, Dewitt; Streiffer, Henry; Jones, Farrell; Lewis, Anthony; Williams, S.

    1991-01-01

    Louisiana's coastal wetlands support a large percentage of the nation's seafood and fur industries, vast deposits of oil and natural gas, habitat for thousands of species of plants and animals, winter nesting grounds and migratory paths for numerous waterfowl, and many recreational resources enjoyed by residents and tourists. Louisiana's wetlands also have the highest rates of coastal erosion and wetland loss in the nation. While numerous studies across many disciplines have been conducted on both local and regional scales, no complete inventory exists for this information. The Louisiana Coastal Geographic Information System Network (LCGISN) is currently being developed to facilitate access to existing data for coastal zone planners, managers, and researchers. The Louisiana Geological Survey (LGS), in cooperation with the LSU Department of Geography and Anthropology, the Computer Aided Design and Geographic Information Systems Research Laboratory (CADGIS), and others, is pursuing this project under the terms of a cooperative agreement with the U.S. Geological Survey. LCGISN is an automated system for searching and retrieving geographic, cartographic, and bibliographic data. By linking original programming with an existing GIS software package and an industry standard relational database management system, LCGISN will provide the capability for users to search for data references by interactively defining the area of interest on a displayed map/image reference background. Several agencies will be networked to provide easy access to a wide variety of information. LCGISN, with its headquarters at LGS, will serve as the central node on the network, providing data format conversions, projection and datum transformations, and storage of several of the most commonly used data sets. Thematic mapper data, USGS 7.5-minute quadrangle map boundaries, political and legal boundaries, major transportation routes, and other digital data will provide a base map to aid the user in

  18. Energy latency tradeoffs for medium access and sleep scheduling in wireless sensor networks

    NASA Astrophysics Data System (ADS)

    Gang, Lu

    Wireless sensor networks are expected to be used in a wide range of applications from environment monitoring to event detection. The key challenge is to provide energy efficient communication; however, latency remains an important concern for many applications that require fast response. The central thesis of this work is that energy efficient medium access and sleep scheduling mechanisms can be designed without necessarily sacrificing application-specific latency performance. We validate this thesis through results from four case studies that cover various aspects of medium access and sleep scheduling design in wireless sensor networks. Our first effort, DMAC, is to design an adaptive low latency and energy efficient MAC for data gathering to reduce the sleep latency. We propose staggered schedule, duty cycle adaptation, data prediction and the use of more-to-send packets to enable seamless packet forwarding under varying traffic load and channel contentions. Simulation and experimental results show significant energy savings and latency reduction while ensuring high data reliability. The second research effort, DESS, investigates the problem of designing sleep schedules in arbitrary network communication topologies to minimize the worst case end-to-end latency (referred to as delay diameter). We develop a novel graph-theoretical formulation, derive and analyze optimal solutions for the tree and ring topologies and heuristics for arbitrary topologies. The third study addresses the problem of minimum latency joint scheduling and routing (MLSR). By constructing a novel delay graph, the optimal joint scheduling and routing can be solved by M node-disjoint paths algorithm under multiple channel model. We further extended the algorithm to handle dynamic traffic changes and topology changes. A heuristic solution is proposed for MLSR under single channel interference. In the fourth study, EEJSPC, we first formulate a fundamental optimization problem that provides tunable

  19. Bexarotene Topical

    MedlinePlus

    ... You may bathe, shower, or swim during your treatment with topical bexarotene, but you should use only a mild, ... your treatment. If you become pregnant during your treatment with topical bexarotene, call your doctor immediately.tell your doctor ...

  20. Principals' Perceptions of Social Networking Access, Its Relationship to Cyberbullying, the Importance of Student Achievement, and the School Environment

    ERIC Educational Resources Information Center

    Townsel, Andrae

    2015-01-01

    The purpose of this study was to examine the principals' perceptions of social networking access and its relationship to cyberbullying, the importance of student achievement, and the school environment across the United States. This research provides some evidence on how principals perceive and understand the threat of cyberbullying and its…

  1. The PrePRINT Network: A New Dynamic in Information Access from the U.S. Department of Energy.

    ERIC Educational Resources Information Center

    Traylor, Terry Dennis

    2001-01-01

    Describes the PrePRINT Network, initiated by the Department of Energy to provide access to online preprints and reprints in the sciences and some areas of technological development. Discusses posting preprints on the Internet to improve scientific communication; and explains other Web-based products created to provide scientists with professional…

  2. Secure Communications in High Speed Fiber Optical Networks Using Code Division Multiple Access (CDMA) Transmission

    SciTech Connect

    Han, I; Bond, S; Welty, R; Du, Y; Yoo, S; Reinhardt, C; Behymer, E; Sperry, V; Kobayashi, N

    2004-02-12

    This project is focused on the development of advanced components and system technologies for secure data transmission on high-speed fiber optic data systems. This work capitalizes on (1) a strong relationship with outstanding faculty at the University of California-Davis who are experts in high speed fiber-optic networks, (2) the realization that code division multiple access (CDMA) is emerging as a bandwidth enhancing technique for fiber optic networks, (3) the realization that CDMA of sufficient complexity forms the basis for almost unbreakable one-time key transmissions, (4) our concepts for superior components for implementing CDMA, (5) our expertise in semiconductor device processing and (6) our Center for Nano and Microtechnology, which is where the majority of the experimental work was done. Here we present a novel device concept, which will push the limits of current technology, and will simultaneously solve system implementation issues by investigating new state-of-the-art fiber technologies. This will enable the development of secure communication systems for the transmission and reception of messages on deployed commercial fiber optic networks, through the CDMA phase encoding of broad bandwidth pulses. CDMA technology has been developed as a multiplexing technology, much like wavelength division multiplexing (WDM) or time division multiplexing (TDM), to increase the potential number of users on a given communication link. A novel application of the techniques created for CDMA is to generate secure communication through physical layer encoding. Physical layer encoding devices are developed which utilize semiconductor waveguides with fast carrier response times to phase encode spectral components of a secure signal. Current commercial technology, most commonly a spatial light modulator, allows phase codes to be changed at rates of only 10's of Hertz ({approx}25ms response). The use of fast (picosecond to nanosecond) carrier dynamics of semiconductors, as

  3. Support of Research and Development Activities via the Internet: NASA's Access Mechanism.

    ERIC Educational Resources Information Center

    Duncan, Denise; And Others

    1993-01-01

    Describes a prototype information access system developed by NASA (National Aeronautics and Space Administration) called NAM (NASA Access Mechanism) to access the Internet for research and development activities. Topics addressed include the Science and Technical Information Program, information needs, networking requirements, functional and…

  4. [Informatics in the School of Medicine of the University of Chile. II. The school network and access to data bases].

    PubMed

    Vivaldi, E A

    1990-12-01

    Projects on informatics at the School of Medicine of the University of Chile are being brought about in accordance with both its institutional goals and present trends in technology. Prominent among the latter are the widespread distribution of autonomous processing power represented by low-cost computers and the ease of communication at local and worldwide levels. Our main project has been the design and start of a computer network that integrates the School's Departments and the geographically dispersed teaching hospitals. The principal services provided by the network are local and international electronic mail, access to data bases, and emulation of mainframe terminals (eg, to run remotely a mainframe's statistics software). Automated bibliographic search has been made available both through remote access to Medline data base and through local usage of compact disc (CD-ROM) versions. Since our network is open, it should become a forceful mean of assisting and integrating the biomedical community throughout the country. PMID:2152674

  5. [Informatics in the School of Medicine of the University of Chile. II. The school network and access to data bases].

    PubMed

    Vivaldi, E A

    1990-12-01

    Projects on informatics at the School of Medicine of the University of Chile are being brought about in accordance with both its institutional goals and present trends in technology. Prominent among the latter are the widespread distribution of autonomous processing power represented by low-cost computers and the ease of communication at local and worldwide levels. Our main project has been the design and start of a computer network that integrates the School's Departments and the geographically dispersed teaching hospitals. The principal services provided by the network are local and international electronic mail, access to data bases, and emulation of mainframe terminals (eg, to run remotely a mainframe's statistics software). Automated bibliographic search has been made available both through remote access to Medline data base and through local usage of compact disc (CD-ROM) versions. Since our network is open, it should become a forceful mean of assisting and integrating the biomedical community throughout the country.

  6. Disparate access to treatment regimens in chronic hepatitis C patients: data from the TRIO network.

    PubMed

    Younossi, Z M; Bacon, B R; Dieterich, D T; Flamm, S L; Kowdley, K; Milligan, S; Tsai, N; Nezam, A

    2016-06-01

    Despite the clinical success in the real-world of all oral hepatitis C virus (HCV) therapy with response rates approaching that seen in the clinical trials, access has been limited by many payers with discussion of prioritization of treatment based upon AASLD guidelines. We evaluated patients in the TRIO network who were prescribed sofosbuvir (SOF)-based regimens to determine reasons for not starting treatment. Trio Health is a disease management company that works in partnership with academic medical centres, community physicians and specialty pharmacies in the United States to optimize care for HCV. Data for 3841 patients prescribed a sofosbuvir-containing regimen between December 2013 and September 2014 were obtained through this programme. Of the entire group, 315 (8%) patients did not start the prescribed sofosbuvir-containing therapy. A total of 141 (45%) of the nonstart patients had a commercial plan as their primary insurance, 137 (44%) were primarily covered by Medicaid, 17 (5%) were primarily covered by Medicare, and 20 (6%) were either without coverage or coverage was not specified. Reasons for nonstarts were varied and overlapping. Only 15 patients (5% of nonstarts) did not start because they were unreachable or failed to complete required testing. Another 39 patients who did not start (12%) were following their physicians' direction to either wait for new treatment options or to hold treatment for an unspecified reason. Insurance-related processes and financial reasons accounted for 254 (81%) of the 315 nonstarts. The remaining 7 (2%) patients did not have a specified reason for not starting treatment. Nonstart rates were highest in the Medicaid-covered population at 35%. Medicare and Commercial nonstart rates were 2% and 6%, respectively. In a matched comparison, patients with commercial coverage were 6.5 times as likely to start SOF-based therapy compared to patients with Medicaid. Despite high SVR rates of SOF-based regimens in clinical practice

  7. An Experimental Performance Measurement of Implemented Wireless Access Point for Interworking Wi-Fi and HSDPA Networks

    NASA Astrophysics Data System (ADS)

    Byun, Tae-Young

    This paper presents a prototype of WAP(Wireless Access Point) that provides the wireless Internet access anywhere. Implemented WAP can be equipped with various wireless WAN interfaces such as WCDMA and HSDPA. WAP in the IP mechanism has to process connection setup procedure to one wireless WAN. Also, WAP can provide connection management procedures to reconnect interrupted connection automatically. By using WAP, several mobile devices such as netbook, UMPC and smart-phone in a moving vehicle can access to HSDPA network simultaneously. So, it has more convenient for using the WAP when there are needs to access wireless Internet more than two mobile devices in restricted spaces such as car, train and ship.

  8. Novel cost-effective PON-to-RoF photonic bridge for multigigabit access networks.

    PubMed

    Aldaya, Ivan; Campuzano, Gabriel; Castañón, Gerardo; Gosset, Christophe

    2013-12-30

    Telecommunication operators are investing significant resources in developing passive optical networks (PONs) to meet the increasing capacity requirements. Therefore, wireless transmission has become the bottleneck for the wireless broadband internet access due to the spectrum saturation. This issue can be solved taking advantage of the huge portions of unused spectrum at high-microwave / millimeter-wave (mm-wave) bands, but their generation is power consuming. Radio over fiber (RoF) is a cost-efficient solution for the distribution of high-frequency broadband signals to remote base stations. We present a novel photonic PON-to-RoF bridge based on heterodyning a PON signal with an unmodulated tone generated by an independent laser. The proposed scheme is transparent to modulation format and can generate RF signals in the entire microwave band. The feasibility of the bridge is experimentally shown converting a 2-Gbps orthogonal frequency division multiplexing PON signal using inexepensive distributed feedback lasers, whose phase noise is cancelled employing an envelope detection based mobile terminal. PMID:24514776

  9. Novel cost-effective PON-to-RoF photonic bridge for multigigabit access networks.

    PubMed

    Aldaya, Ivan; Campuzano, Gabriel; Castañón, Gerardo; Gosset, Christophe

    2013-12-30

    Telecommunication operators are investing significant resources in developing passive optical networks (PONs) to meet the increasing capacity requirements. Therefore, wireless transmission has become the bottleneck for the wireless broadband internet access due to the spectrum saturation. This issue can be solved taking advantage of the huge portions of unused spectrum at high-microwave / millimeter-wave (mm-wave) bands, but their generation is power consuming. Radio over fiber (RoF) is a cost-efficient solution for the distribution of high-frequency broadband signals to remote base stations. We present a novel photonic PON-to-RoF bridge based on heterodyning a PON signal with an unmodulated tone generated by an independent laser. The proposed scheme is transparent to modulation format and can generate RF signals in the entire microwave band. The feasibility of the bridge is experimentally shown converting a 2-Gbps orthogonal frequency division multiplexing PON signal using inexepensive distributed feedback lasers, whose phase noise is cancelled employing an envelope detection based mobile terminal.

  10. TRIP database 2.0: a manually curated information hub for accessing TRP channel interaction network.

    PubMed

    Shin, Young-Cheul; Shin, Soo-Yong; Chun, Jung Nyeo; Cho, Hyeon Sung; Lim, Jin Muk; Kim, Hong-Gee; So, Insuk; Kwon, Dongseop; Jeon, Ju-Hong

    2012-01-01

    Transient receptor potential (TRP) channels are a family of Ca(2+)-permeable cation channels that play a crucial role in biological and disease processes. To advance TRP channel research, we previously created the TRIP (TRansient receptor potential channel-Interacting Protein) Database, a manually curated database that compiles scattered information on TRP channel protein-protein interactions (PPIs). However, the database needs to be improved for information accessibility and data utilization. Here, we present the TRIP Database 2.0 (http://www.trpchannel.org) in which many helpful, user-friendly web interfaces have been developed to facilitate knowledge acquisition and inspire new approaches to studying TRP channel functions: 1) the PPI information found in the supplementary data of referred articles was curated; 2) the PPI summary matrix enables users to intuitively grasp overall PPI information; 3) the search capability has been expanded to retrieve information from 'PubMed' and 'PIE the search' (a specialized search engine for PPI-related articles); and 4) the PPI data are available as sif files for network visualization and analysis using 'Cytoscape'. Therefore, our TRIP Database 2.0 is an information hub that works toward advancing data-driven TRP channel research.

  11. Performance of an optical equalizer in a 10 G wavelength converting optical access network.

    PubMed

    Mendinueta, José Manuel D; Cao, Bowen; Thomsen, Benn C; Mitchell, John E

    2011-12-12

    A centralized optical processing unit (COPU) that functions both as a wavelength converter (WC) and optical burst equaliser in a 10 Gb/s wavelength-converting optical access network is proposed and experimentally characterized. This COPU is designed to consolidate drifting wavelengths generated with an uncooled laser in the upstream direction into a stable wavelength channel for WDM backhaul transmission and to equalize the optical loud/soft burst power in order to relax the burst-mode receiver dynamic range requirement. The COPU consists of an optical power equaliser composed of two cascaded SOAs followed by a WC. Using an optical packet generator and a DC-coupled PIN-based digital burst-mode receiver, the COPU is characterized in terms of payload-BER for back-to-back and backhaul transmission distances of 22, 40, and 62 km. We show that there is a compromise between the receiver sensitivity and overload points that can be optimized tuning the WC operating point for a particular backhaul fiber transmission distance. Using the optimized settings, sensitivities of -30.94, -30.17, and -27.26 dBm with overloads of -9.3, -5, and >-5 dBm were demonstrated for backhaul transmission distances of 22, 40 and 62 km, respectively. PMID:22274023

  12. Efinaconazole Topical

    MedlinePlus

    ... treat fungal toenail infections (infections that may cause nail discoloration, splitting, or pain). Efinaconazole topical solution is ... antifungals. It works by stopping the growth of nail fungus.

  13. MaNIDA: Insight into the German Marine Network for Integrated Data Access

    NASA Astrophysics Data System (ADS)

    Schäfer, Angela; Scientific MaNIDA Team

    2013-04-01

    The Marine Network for Integrated Data Access (MaNIDA) builds a sustainable e-Infrastructure to support discovery and re-use of data from distinct marine and earth science data providers in Germany (see ESSI1.2 and ESSI2.2). Thereby we implement the "Data Portal of German Marine Research" for coherent discovery, view, download and dissemination of aggregated content. MaNIDA receives a unique momentum from the cooperation and financial partnership between main German marine research institutes (AWI, MARUM, HZG, GEOMAR, Uni Hamburg, Uni Kiel, Uni Bremen) and the Federal Maritime and Hydrographic Agency as well as active participation in international and major EU-initiatives (ICSU, GEOSS, SeaDataNet, EMODNET, ODIP). Together with a coherent management strategy coordinated by the Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research, sustainability will be achieved via the long-term commitment of framework funding by the Helmholtz Association, Germany's largest scientific research organization for large-scale facilities and scientific infrastructure. Strategic Aims The installation of the "Data Portal of German Marine Research" will address the urgent demands of the German research community for reliable and easy access to marine research data at one single point of access and truth. Primary focus will be given to data derived from nationally operated research and monitoring facilities (vessels, observatories, alert systems, etc), whereby related contextual content and publications will become an integral part of the aggregation effort. For the scientific community we define responsibilities and commitments across partners while complementing existing data repositories and the new portal with well-articulated workflows from the instrument to the data product. Necessary level of quality assurance and user support will be implemented to achieve substantial enhancements in the whole lifecycle management of marine scientific data. The creation of a data

  14. Networks.

    ERIC Educational Resources Information Center

    Cerf, Vinton G.

    1991-01-01

    The demands placed on the networks transporting the information and knowledge generated by the increased diversity and sophistication of computational machinery are described. What is needed to support this increased flow, the structures already in place, and what must be built are topics of discussion. (KR)

  15. Transportation: Topic Paper E.

    ERIC Educational Resources Information Center

    National Council on the Handicapped, Washington, DC.

    As one of a series of topic papers assessing federal laws and programs affecting persons with disabilities, this paper reviews the issue of transportation services. In the area of urban mass transit, four relevant pieces of legislation and public transportation accessibility regulations are cited, and cost issues are explored. Paratransit systems,…

  16. Study on the energy-efficient scheme based on the interconnection of optical-network-units for next generation optical access network

    NASA Astrophysics Data System (ADS)

    Lv, Yunxin; Jiang, Ning; Qiu, Kun; Xue, Chenpeng

    2014-12-01

    An energy-efficient scheme based on the interconnection of optical network unit (ONU) is introduced, which can significantly reduce the energy consumption of the low-traffic operation. The energy consumption model for the ONU-interconnected optical access network (OAN) based on the electronic switch (ES) technology is established, and the energy efficiency of the proposed scheme is analyzed and compared with that of the OAN using optical switch (OS). The simulation results demonstrate that the ONU-interconnected scheme can efficiently reduce the energy consumption of OAN, and it shows a good energy consumption performance under daily traffic model.

  17. Performance evaluation of multilevel modulation formats using partial response for capacity upgrade in access network with limited electronic bandwidth

    NASA Astrophysics Data System (ADS)

    Madsen, Peter; Frejstrup Suhr, Lau; Sebastian Rodriguez, Juan; Tafur Monroy, Idelfonso; Vegas Olmos, Juan José

    2016-09-01

    We present a successful experimental evaluation of 4 level Pulse Amplitude Modulation (4-PAM) and Duobinary modulation. An experimental performance evaluation is presented for Duobinary 4 PAM and other modulation formats. All modulation formants used, may be considered to be implemented in future Passive Optical Network (PON) class access networks with limited electrical bandwidth. We compared NRZ, Duobinary, 4-PAM and Duobinary 4-PAM operating at 9 Gbaud over 20 km single mode fiber. The results provides an insight and guidelines on the utilization of these advanced modulation formats.

  18. Morning REM Sleep Naps Facilitate Broad Access to Emotional Semantic Networks

    PubMed Central

    Carr, Michelle; Nielsen, Tore

    2015-01-01

    Study Objectives: The goals of the study were to assess semantic priming to emotion and nonemotion cue words using a novel measure of associational breadth for participants who either took rapid eye movement (REM) or nonrapid eye movement (NREM) naps or who remained awake, and to assess the relation of priming to REM sleep consolidation and REM sleep inertia effects. Design: The associational breadth task was applied in both a priming condition, where cue words were signaled to be memorized prior to sleep (primed), and a nonpriming condition, where cue words were not memorized (nonprimed). Cue words were either emotional (positive, negative) or nonemotional. Participants were randomly assigned to either an awake (WAKE) or a sleep condition, which was subsequently split into NREM or REM groups depending on stage at awakening. Setting: Hospital-based sleep laboratory. Participants: Fifty-eight healthy participants (22 male) ages 18 to 35 y (mean age = 23.3 ± 4.08 y). Measurements and Results: The REM group scored higher than the NREM or WAKE groups on primed, but not nonprimed emotional cue words; the effect was stronger for positive than for negative cue words. However, REM time and percent correlated negatively with degree of emotional priming. Priming occurred for REM awakenings but not for NREM awakenings, even when the latter sleep episodes contained some REM sleep. Conclusions: Associational breadth may be selectively consolidated during REM sleep for stimuli that have been tagged as important for future memory retrieval. That priming decreased with REM time and was higher only for REM sleep awakenings is consistent with two explanatory REM sleep processes: REM sleep consolidation serving emotional downregulation and REM sleep inertia. Citation: Carr M, Nielsen T. Morning REM sleep naps facilitate broad access to emotional semantic networks. SLEEP 2015;38(3):433–443. PMID:25409100

  19. Dynamic Key Management Schemes for Secure Group Access Control Using Hierarchical Clustering in Mobile Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Tsaur, Woei-Jiunn; Pai, Haw-Tyng

    2008-11-01

    The applications of group computing and communication motivate the requirement to provide group access control in mobile ad hoc networks (MANETs). The operation in MANETs' groups performs a decentralized manner and accommodated membership dynamically. Moreover, due to lack of centralized control, MANETs' groups are inherently insecure and vulnerable to attacks from both within and outside the groups. Such features make access control more challenging in MANETs. Recently, several researchers have proposed group access control mechanisms in MANETs based on a variety of threshold signatures. However, these mechanisms cannot actually satisfy MANETs' dynamic environments. This is because the threshold-based mechanisms cannot be achieved when the number of members is not up to the threshold value. Hence, by combining the efficient elliptic curve cryptosystem, self-certified public key cryptosystem and secure filter technique, we construct dynamic key management schemes based on hierarchical clustering for securing group access control in MANETs. Specifically, the proposed schemes can constantly accomplish secure group access control only by renewing the secure filters of few cluster heads, when a cluster head joins or leaves a cross-cluster. In such a new way, we can find that the proposed group access control scheme can be very effective for securing practical applications in MANETs.

  20. Authority of the Food and Drug Administration to require data access and control use rights in the Sentinel data network.

    PubMed

    Evans, Barbara J

    2010-01-01

    The Food and Drug Administration Amendments Act of 2007 (FDAAA) authorized the U.S. Food and Drug Administration (FDA) to develop a 100-million-person health data network known as the Sentinel system. When fully operational, the Sentinel network will offer a very rich, very large health data resource that has the potential to become one of history's most powerful engines of biomedical innovation and clinical translation of discoveries. Who controls this asset will be a matter of great scientific and commercial importance. This article explores two key questions--data access and use rights--that are under debate as various parties jostle for control of the network: First, does FDA have legal authority to require private healthcare data environments--such as insurers, healthcare providers, pharmacists and other entities that hold data in administrative and clinical databases--to make data available for inclusion in the network? Second, who will decide how the network is used, once it is built? The article explains why a neutral analysis of these questions is essential as FDA designs the governance framework for protecting the diverse stakeholders who will be touched by the Sentinel network. The conclusion describes threats to network operations, including federal and state constitutional claims and state legislative interventions, which could arise if FDA fails to devote timely attention to these issues.

  1. Multi-service small-cell cloud wired/wireless access network based on tunable optical frequency comb

    NASA Astrophysics Data System (ADS)

    Xiang, Yu; Zhou, Kun; Yang, Liu; Pan, Lei; Liao, Zhen-wan; Zhang, Qiang

    2015-11-01

    In this paper, we demonstrate a novel multi-service wired/wireless integrated access architecture of cloud radio access network (C-RAN) based on radio-over-fiber passive optical network (RoF-PON) system, which utilizes scalable multiple- frequency millimeter-wave (MF-MMW) generation based on tunable optical frequency comb (TOFC). In the baseband unit (BBU) pool, the generated optical comb lines are modulated into wired, RoF and WiFi/WiMAX signals, respectively. The multi-frequency RoF signals are generated by beating the optical comb line pairs in the small cell. The WiFi/WiMAX signals are demodulated after passing through the band pass filter (BPF) and band stop filter (BSF), respectively, whereas the wired signal can be received directly. The feasibility and scalability of the proposed multi-service wired/wireless integrated C-RAN are confirmed by the simulations.

  2. Advertisement-Based Energy Efficient Medium Access Protocols for Wireless Sensor Networks

    NASA Astrophysics Data System (ADS)

    Ray, Surjya Sarathi

    One of the main challenges that prevents the large-scale deployment of Wireless Sensor Networks (WSNs) is providing the applications with the required quality of service (QoS) given the sensor nodes' limited energy supplies. WSNs are an important tool in supporting applications ranging from environmental and industrial monitoring, to battlefield surveillance and traffic control, among others. Most of these applications require sensors to function for long periods of time without human intervention and without battery replacement. Therefore, energy conservation is one of the main goals for protocols for WSNs. Energy conservation can be performed in different layers of the protocol stack. In particular, as the medium access control (MAC) layer can access and control the radio directly, large energy savings is possible through intelligent MAC protocol design. To maximize the network lifetime, MAC protocols for WSNs aim to minimize idle listening of the sensor nodes, packet collisions, and overhearing. Several approaches such as duty cycling and low power listening have been proposed at the MAC layer to achieve energy efficiency. In this thesis, I explore the possibility of further energy savings through the advertisement of data packets in the MAC layer. In the first part of my research, I propose Advertisement-MAC or ADV-MAC, a new MAC protocol for WSNs that utilizes the concept of advertising for data contention. This technique lets nodes listen dynamically to any desired transmission and sleep during transmissions not of interest. This minimizes the energy lost in idle listening and overhearing while maintaining an adaptive duty cycle to handle variable loads. Additionally, ADV-MAC enables energy efficient MAC-level multicasting. An analytical model for the packet delivery ratio and the energy consumption of the protocol is also proposed. The analytical model is verified with simulations and is used to choose an optimal value of the advertisement period

  3. Advertisement-Based Energy Efficient Medium Access Protocols for Wireless Sensor Networks

    NASA Astrophysics Data System (ADS)

    Ray, Surjya Sarathi

    One of the main challenges that prevents the large-scale deployment of Wireless Sensor Networks (WSNs) is providing the applications with the required quality of service (QoS) given the sensor nodes' limited energy supplies. WSNs are an important tool in supporting applications ranging from environmental and industrial monitoring, to battlefield surveillance and traffic control, among others. Most of these applications require sensors to function for long periods of time without human intervention and without battery replacement. Therefore, energy conservation is one of the main goals for protocols for WSNs. Energy conservation can be performed in different layers of the protocol stack. In particular, as the medium access control (MAC) layer can access and control the radio directly, large energy savings is possible through intelligent MAC protocol design. To maximize the network lifetime, MAC protocols for WSNs aim to minimize idle listening of the sensor nodes, packet collisions, and overhearing. Several approaches such as duty cycling and low power listening have been proposed at the MAC layer to achieve energy efficiency. In this thesis, I explore the possibility of further energy savings through the advertisement of data packets in the MAC layer. In the first part of my research, I propose Advertisement-MAC or ADV-MAC, a new MAC protocol for WSNs that utilizes the concept of advertising for data contention. This technique lets nodes listen dynamically to any desired transmission and sleep during transmissions not of interest. This minimizes the energy lost in idle listening and overhearing while maintaining an adaptive duty cycle to handle variable loads. Additionally, ADV-MAC enables energy efficient MAC-level multicasting. An analytical model for the packet delivery ratio and the energy consumption of the protocol is also proposed. The analytical model is verified with simulations and is used to choose an optimal value of the advertisement period

  4. C+L band wavelength division multiplexing access network with distributed-controlled protection architecture

    NASA Astrophysics Data System (ADS)

    Yeh, Chien Hung; Chow, Chi Wai

    2011-12-01

    In this work, we propose and experimentally demonstrate a novel distributed-controlled protection architecture for automatic and fast network restoration in wavelength division multiplexing-passive optical network (WDM-PON). The proposed scheme can support both C and L bands. Besides, duplication of network equipments, such as optical networking unit (ONU) or optical line terminal, is not required. In this distributed-controlled system, each ONU can always keep track of the network status. Hence, this can facilitate the network manage by removing the work loads from the central office. Besides, the proposed scheme can tolerate simultaneous fiber cuts in the feeder and distributed fibers.

  5. Accessibility, searchability, transparency and engagement of soil carbon data: The International Soil Carbon Network

    NASA Astrophysics Data System (ADS)

    Harden, Jennifer W.; Hugelius, Gustaf; Koven, Charlie; Sulman, Ben; O'Donnell, Jon; He, Yujie

    2016-04-01

    Soils are capacitors for carbon and water entering and exiting through land-atmosphere exchange. Capturing the spatiotemporal variations in soil C exchange through monitoring and modeling is difficult in part because data are reported unevenly across spatial, temporal, and management scales and in part because the unit of measure generally involves destructive harvest or non-recurrent measurements. In order to improve our fundamental basis for understanding soil C exchange, a multi-user, open source, searchable database and network of scientists has been formed. The International Soil Carbon Network (ISCN) is a self-chartered, member-based and member-owned network of scientists dedicated to soil carbon science. Attributes of the ISCN include 1) Targeted ISCN Action Groups which represent teams of motivated researchers that propose and pursue specific soil C research questions with the aim of synthesizing seminal articles regarding soil C fate. 2) Datasets to date contributed by institutions and individuals to a comprehensive, searchable open-access database that currently includes over 70,000 geolocated profiles for which soil C and other soil properties. 3) Derivative products resulting from the database, including depth attenuation attributes for C concentration and storage; C storage maps; and model-based assessments of emission/sequestration for future climate scenarios. Several examples illustrate the power of such a database and its engagement with the science community. First, a simplified, data-constrained global ecosystem model estimated a global sensitivity of permafrost soil carbon to climate change (g sensitivity) of -14 to -19 Pg C °C-1 of warming on a 100 years time scale. Second, using mathematical characterizations of depth profiles for organic carbon storage, C at the soil surface reflects Net Primary Production (NPP) and its allotment as moss or litter, while e-folding depths are correlated to rooting depth. Third, storage of deep C is highly

  6. Clindamycin Topical

    MedlinePlus

    ... topical clindamycin.you should know that abrasive or medicated soaps and skin products that contain alcohol may ... in, tightly closed, and out of reach of children. Store it at room temperature and away from ...

  7. Fluorouracil Topical

    MedlinePlus

    ... caused by years of too much exposure to sunlight). Fluorouracil cream and topical solution are also used ... plan to avoid unnecessary or prolonged exposure to sunlight and UV light (such as tanning booths) and ...

  8. Mometasone Topical

    MedlinePlus

    Mometasone comes as a topical cream, ointment, and lotion. It usually is applied externally once a day. ... affected skin areas once daily.To apply the lotion, place a few drops on the affected areas ...

  9. Dapsone Topical

    MedlinePlus

    Dapsone topical is used to treat acne. Dapsone is in a class of medications called sulfone antibiotics. It works ... taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring ...

  10. Bimatoprost Topical

    MedlinePlus

    ... much medication. Talk to your doctor about using topical bimatoprost if you are also using the eyedrops.tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking ...

  11. Hot topics for leadership development.

    PubMed

    Bleich, Michael R

    2015-02-01

    Three areas stand out from a health systems perspective that should be on the development agenda for all leaders. These topics include population health, predictive analytics, and supply chain management. Together, these topics address access, quality, and cost management. PMID:25633301

  12. Accurate prediction of solvent accessibility using neural networks-based regression.

    PubMed

    Adamczak, Rafał; Porollo, Aleksey; Meller, Jarosław

    2004-09-01

    Accurate prediction of relative solvent accessibilities (RSAs) of amino acid residues in proteins may be used to facilitate protein structure prediction and functional annotation. Toward that goal we developed a novel method for improved prediction of RSAs. Contrary to other machine learning-based methods from the literature, we do not impose a classification problem with arbitrary boundaries between the classes. Instead, we seek a continuous approximation of the real-value RSA using nonlinear regression, with several feed forward and recurrent neural networks, which are then combined into a consensus predictor. A set of 860 protein structures derived from the PFAM database was used for training, whereas validation of the results was carefully performed on several nonredundant control sets comprising a total of 603 structures derived from new Protein Data Bank structures and had no homology to proteins included in the training. Two classes of alternative predictors were developed for comparison with the regression-based approach: one based on the standard classification approach and the other based on a semicontinuous approximation with the so-called thermometer encoding. Furthermore, a weighted approximation, with errors being scaled by the observed levels of variability in RSA for equivalent residues in families of homologous structures, was applied in order to improve the results. The effects of including evolutionary profiles and the growth of sequence databases were assessed. In accord with the observed levels of variability in RSA for different ranges of RSA values, the regression accuracy is higher for buried than for exposed residues, with overall 15.3-15.8% mean absolute errors and correlation coefficients between the predicted and experimental values of 0.64-0.67 on different control sets. The new method outperforms classification-based algorithms when the real value predictions are projected onto two-class classification problems with several commonly

  13. Spotlight Topics

    NASA Astrophysics Data System (ADS)

    A Spotlight Topic consists of a set of two or more review articles focused on a specific subject in surface science. The topics are recommended by the Board of Editors. A topic may be chosen because it is particularly new or fast-breaking, thus deserving introduction to the general readership. Or, it may be because a topic is especially controversial or confusing, requiring clarification by experts. Each review will give a critical assessment rather than an encyclopedic report. While our editors always will insist on fairness and accuracy, any review which forwards an opinion is bound to be somewhat subjective. Therefore, it is the editors' wish that the set of reviews written by different authors on the same subject matter will provide a broad and balanced viewpoint. It is often the case that an author who is an expert in a technique or method may be especially enthusiastic or critical about this technique or method. A companion review in the set may provide a different viewpoint. We are hopeful that the reader, after studying these reviews and checking some of the key references, will obtain an informed opinion of the subject. We think the set of reviews in a spotlight area will considerably shorten the ``learning time'' that a nonexpert would otherwise need to become knowledgeable about a subject. In this issue, we feature a spotlight topic on oxide surfaces. The set contains an overview article by Jacques Jupille, and four articles written by G. Pacchioni, F. Cosandey and T. E. Madey, B. G. Daniels, R. Lindsay and G. Thornton, and C. Noguera respectively. Of these, the article by Pacchioni has already appeared in SRL 7, 277 (2000). The other three articles appear in this issue. A reader who wishes to suggest a spotlight topic or recommend authors to write such reviews should contact the Editor-in-Chief. We would like to hear from you.

  14. Network analysis reveals the relationship among wood properties, gene expression levels and genotypes of natural Populus trichocarpa accessions.

    PubMed

    Porth, Ilga; Klápště, Jaroslav; Skyba, Oleksandr; Friedmann, Michael C; Hannemann, Jan; Ehlting, Juergen; El-Kassaby, Yousry A; Mansfield, Shawn D; Douglas, Carl J

    2013-11-01

    High-throughput approaches have been widely applied to elucidate the genetic underpinnings of industrially important wood properties. Wood traits are polygenic in nature, but gene hierarchies can be assessed to identify the most important gene variants controlling specific traits within complex networks defining the overall wood phenotype. We tested a large set of genetic, genomic, and phenotypic information in an integrative approach to predict wood properties in Populus trichocarpa. Nine-yr-old natural P. trichocarpa trees including accessions with high contrasts in six traits related to wood chemistry and ultrastructure were profiled for gene expression on 49k Nimblegen (Roche NimbleGen Inc., Madison, WI, USA) array elements and for 28,831 polymorphic single nucleotide polymorphisms (SNPs). Pre-selected transcripts and SNPs with high statistical dependence on phenotypic traits were used in Bayesian network learning procedures with a stepwise K2 algorithm to infer phenotype-centric networks. Transcripts were pre-selected at a much lower logarithm of Bayes factor (logBF) threshold than SNPs and were not accommodated in the networks. Using persistent variables, we constructed cross-validated networks for variability in wood attributes, which contained four to six variables with 94-100% predictive accuracy. Accommodated gene variants revealed the hierarchy in the genetic architecture that underpins substantial phenotypic variability, and represent new tools to support the maximization of response to selection.

  15. Promoting Access to Renal Transplantation: The Role of Social Support Networks in Completing Pre-transplant Evaluations

    PubMed Central

    Hicks, Leroi S.; Keogh, Joseph H.; Epstein, Arnold M.; Ayanian, John Z.

    2008-01-01

    Background Completing pre-transplant evaluations may be a greater barrier to renal transplantation for blacks with end-stage renal disease (ESRD) than for whites. Objective To determine whether social support networks facilitate completing the pre-transplant evaluation and reduce racial disparities in this aspect of care. Design, Setting, and Participants We surveyed 742 black and white ESRD patients in four regional networks 9 months after they initiated dialysis in 1996 and 1997. Patients reported instrumental support networks (number of friends or family to help with daily activities), emotional support networks (number of friends or family available for counsel on personal problems) and dialysis center support (support from dialysis center staff and patients). The completion of pre-transplant evaluations, including preoperative risk stratification and testing, was determined by medical record reviews. Outcome Measurement Complete renal pre-transplant evaluations. Results Compared to patients with low levels of instrumental support, those with high levels were more likely to have complete evaluations (25% versus 46%, respectively, p < .001). In adjusted analyses, high levels of instrumental support were associated with higher rates of complete evaluations among black women (p < .05), white women (p < .05), and white men (p < .05), but not black men. Among black men, but not other groups, private insurance was a significant predictor of complete evaluations. Conclusions Instrumental support networks may facilitate completing renal pre-transplant evaluations. Clinical interventions that supplement instrumental support should be evaluated to improve access to renal transplantation. Access to supplemental insurance may also promote complete evaluations for black patients. PMID:18478302

  16. Using a network menu and the UMLS Information Sources Map to facilitate access to online reference materials.

    PubMed Central

    Clyman, J I; Powsner, S M; Paton, J A; Miller, P L

    1993-01-01

    As computer technology advances, clinicians and biomedical researchers are becoming more dependent upon information from online databases and information systems. By using specially configured computer workstations and high-speed computer networks, it is now possible to access this information in a rapid and straightforward manner. To empower users by providing these capabilities, the authors are assembling a variety of network workstations to be located throughout Yale-New Haven Medical Center. At the heart of the workstation is NetMenu, a program designed to help users connect to a number of important online information systems, including a hospital order entry and results reporting system, a drug reference, bibliographic retrieval systems, and educational programs. In addition, as part of the National Library of Medicine's Unified Medical Language System (UMLS) project, the authors have developed a local prototype of the UMLS Information Sources Map (ISM) and a companion query assistant program to complement the NetMenu in helping users select and connect automatically to information services relevant to a particular question. The ISM query assistant draws from a listing of many online information sources accessible via local and international networks. PMID:8472006

  17. Challenges and Opportunities of Information Technology in the 90s. Track V: Managing Telecommunications and Networking.

    ERIC Educational Resources Information Center

    CAUSE, Boulder, CO.

    Six papers from the 1990 CAUSE conference's Track V, Managing Telecommunications and Networking are presented. Topics address such subjects as network funding, support services, access to networks, improvement of instruction through networks, and image transmission. Papers and their authors are as follows: "What's New in Telecommunication?" (Gene…

  18. Improved Iterative Decoding of Network-Channel Codes for Multiple-Access Relay Channel.

    PubMed

    Majumder, Saikat; Verma, Shrish

    2015-01-01

    Cooperative communication using relay nodes is one of the most effective means of exploiting space diversity for low cost nodes in wireless network. In cooperative communication, users, besides communicating their own information, also relay the information of other users. In this paper we investigate a scheme where cooperation is achieved using a common relay node which performs network coding to provide space diversity for two information nodes transmitting to a base station. We propose a scheme which uses Reed-Solomon error correcting code for encoding the information bit at the user nodes and convolutional code as network code, instead of XOR based network coding. Based on this encoder, we propose iterative soft decoding of joint network-channel code by treating it as a concatenated Reed-Solomon convolutional code. Simulation results show significant improvement in performance compared to existing scheme based on compound codes.

  19. Improved Iterative Decoding of Network-Channel Codes for Multiple-Access Relay Channel

    PubMed Central

    Majumder, Saikat; Verma, Shrish

    2015-01-01

    Cooperative communication using relay nodes is one of the most effective means of exploiting space diversity for low cost nodes in wireless network. In cooperative communication, users, besides communicating their own information, also relay the information of other users. In this paper we investigate a scheme where cooperation is achieved using a common relay node which performs network coding to provide space diversity for two information nodes transmitting to a base station. We propose a scheme which uses Reed-Solomon error correcting code for encoding the information bit at the user nodes and convolutional code as network code, instead of XOR based network coding. Based on this encoder, we propose iterative soft decoding of joint network-channel code by treating it as a concatenated Reed-Solomon convolutional code. Simulation results show significant improvement in performance compared to existing scheme based on compound codes. PMID:27347526

  20. Massive Access Control Aided by Knowledge-Extraction for Co-Existing Periodic and Random Services over Wireless Clinical Networks.

    PubMed

    Du, Qinghe; Zhao, Weidong; Li, Weimin; Zhang, Xuelin; Sun, Bo; Song, Houbing; Ren, Pinyi; Sun, Li; Wang, Yichen

    2016-07-01

    The prosperity of e-health is boosted by fast development of medical devices with wireless communications capability such as wearable devices, tiny sensors, monitoring equipments, etc., which are randomly distributed in clinic environments. The drastically-increasing population of such devices imposes new challenges on the limited wireless resources. To relieve this problem, key knowledge needs to be extracted from massive connection attempts dispersed in the air towards efficient access control. In this paper, a hybrid periodic-random massive access (HPRMA) scheme for wireless clinical networks employing ultra-narrow band (UNB) techniques is proposed. In particular, the proposed scheme towards accommodating a large population of devices include the following new features. On one hand, it can dynamically adjust the resource allocated for coexisting periodic and random services based on the traffic load learned from signal collision status. On the other hand, the resource allocation within periodic services is thoroughly designed to simultaneously align with the timing requests of differentiated services. Abundant simulation results are also presented to demonstrate the superiority of the proposed HPRMA scheme over baseline schemes including time-division multiple access (TDMA) and random access approach, in terms of channel utilization efficiency, packet drop ratio, etc., for the support of massive devices' services.

  1. Increment of Access Points in Integrated System of Wavelength Division Multiplexed Passive Optical Network Radio over Fiber.

    PubMed

    Amiri, I S; Alavi, S E; Soltanian, M R K; Fisal, N; Supa'at, A S M; Ahmad, H

    2015-01-01

    This paper describes a novel technique to increase the numbers of access points (APs) in a wavelength division multiplexed-passive optical network (WDM-PON) integrated in a 100 GHz radio-over-fiber (RoF). Eight multi-carriers separated by 25 GHz intervals were generated in the range of 193.025 to 193.200 THz using a microring resonator (MRR) system incorporating an add-drop filter system. All optically generated multi-carriers were utilized in an integrated system of WDM-PON-RoF for transmission of four 43.6 Gb/sec orthogonal frequency division multiplexing (OFDM) signals. Results showed that an acceptable BER variation for different path lengths up to 25 km was achievable for all four access points and thus the transmission of four OFDM channels is feasible for a 25 km standard single mode fiber (SSMF) path length. PMID:26153536

  2. Novel Scheme of Carrier Tri-reuse and Distribution Fiber Protection Based on Round Shift Method in Optical Access Network

    NASA Astrophysics Data System (ADS)

    Chen, Haibin; Gan, Chaoqin; Yin, Maojun; Ni, Cuiping

    2015-06-01

    A novel architecture of optical access network based on round shift method is proposed. Round shift method is composed by round service mode of carriers and cycle characteristic of 2×N arrayed waveguide grating (AWG). By utilizing the round service mode, every carrier is tri-reused to provide service for three different optical network units. Besides, in remote node, the 2×3N AWG can be replaced by three 2×N AWGs and AWGs' channel spacing is increased. So, the demand on RN's AWGs is decreased. Furthermore, based on the cycle characteristic of 2×N AWG, a 1+1 protection scheme is presented to provide independent protection for distribution fibers. Simulation and analysis show the proposed scheme works well.

  3. Fencing network direct memory access data transfers in a parallel active messaging interface of a parallel computer

    DOEpatents

    Blocksome, Michael A.; Mamidala, Amith R.

    2015-07-14

    Fencing direct memory access (`DMA`) data transfers in a parallel active messaging interface (`PAMI`) of a parallel computer, the PAMI including data communications endpoints, each endpoint including specifications of a client, a context, and a task, the endpoints coupled for data communications through the PAMI and through DMA controllers operatively coupled to a deterministic data communications network through which the DMA controllers deliver data communications deterministically, including initiating execution through the PAMI of an ordered sequence of active DMA instructions for DMA data transfers between two endpoints, effecting deterministic DMA data transfers through a DMA controller and the deterministic data communications network; and executing through the PAMI, with no FENCE accounting for DMA data transfers, an active FENCE instruction, the FENCE instruction completing execution only after completion of all DMA instructions initiated prior to execution of the FENCE instruction for DMA data transfers between the two endpoints.

  4. Fencing network direct memory access data transfers in a parallel active messaging interface of a parallel computer

    DOEpatents

    Blocksome, Michael A.; Mamidala, Amith R.

    2015-07-07

    Fencing direct memory access (`DMA`) data transfers in a parallel active messaging interface (`PAMI`) of a parallel computer, the PAMI including data communications endpoints, each endpoint including specifications of a client, a context, and a task, the endpoints coupled for data communications through the PAMI and through DMA controllers operatively coupled to a deterministic data communications network through which the DMA controllers deliver data communications deterministically, including initiating execution through the PAMI of an ordered sequence of active DMA instructions for DMA data transfers between two endpoints, effecting deterministic DMA data transfers through a DMA controller and the deterministic data communications network; and executing through the PAMI, with no FENCE accounting for DMA data transfers, an active FENCE instruction, the FENCE instruction completing execution only after completion of all DMA instructions initiated prior to execution of the FENCE instruction for DMA data transfers between the two endpoints.

  5. The Evolving National Information Network: Background and Challenges. A Report of the Technology Assessment Advisory Committee to the Commission on Preservation and Access.

    ERIC Educational Resources Information Center

    Van Houweling, Douglas E.; McGill, Michael J.

    The rapidly developing and changing networking and telecommunications environment now being implemented in the United States and across the globe is explored. The creation of a flexible and inexpensive digital network allowing instantaneous access by any individual to information of any type is now within our grasp. A primer on the technology…

  6. Topical anesthesia.

    PubMed

    Kumar, Mritunjay; Chawla, Rajiv; Goyal, Manish

    2015-01-01

    Topical anesthetics are being widely used in numerous medical and surgical sub-specialties such as anesthesia, ophthalmology, otorhinolaryngology, dentistry, urology, and aesthetic surgery. They cause superficial loss of pain sensation after direct application. Their delivery and effectiveness can be enhanced by using free bases; by increasing the drug concentration, lowering the melting point; by using physical and chemical permeation enhancers and lipid delivery vesicles. Various topical anesthetic agents available for use are eutectic mixture of local anesthetics, ELA-max, lidocaine, epinephrine, tetracaine, bupivanor, 4% tetracaine, benzocaine, proparacaine, Betacaine-LA, topicaine, lidoderm, S-caine patch™ and local anesthetic peel. While using them, careful attention must be paid to their pharmacology, area and duration of application, age and weight of the patients and possible side-effects.

  7. Topical anesthesia

    PubMed Central

    Kumar, Mritunjay; Chawla, Rajiv; Goyal, Manish

    2015-01-01

    Topical anesthetics are being widely used in numerous medical and surgical sub-specialties such as anesthesia, ophthalmology, otorhinolaryngology, dentistry, urology, and aesthetic surgery. They cause superficial loss of pain sensation after direct application. Their delivery and effectiveness can be enhanced by using free bases; by increasing the drug concentration, lowering the melting point; by using physical and chemical permeation enhancers and lipid delivery vesicles. Various topical anesthetic agents available for use are eutectic mixture of local anesthetics, ELA-max, lidocaine, epinephrine, tetracaine, bupivanor, 4% tetracaine, benzocaine, proparacaine, Betacaine-LA, topicaine, lidoderm, S-caine patch™ and local anesthetic peel. While using them, careful attention must be paid to their pharmacology, area and duration of application, age and weight of the patients and possible side-effects. PMID:26702198

  8. Iowa Communications Network Enhancing Education in Iowa.

    ERIC Educational Resources Information Center

    Ivanovic, Greta

    1995-01-01

    Describes the Iowa Communications Network, a statewide fiber optic network capable of transporting interactive, two-way audio, video, voice, and data signals. Topics include statewide cooperation among educational and state organizations; classroom design, including interactive classrooms; access to the Internet; and use by noneducational…

  9. Impairments Computation for Routing Purposes in a Transparent-Access Optical Network Based on Optical CDMA and WDM

    NASA Astrophysics Data System (ADS)

    Musa, Ahmed

    2016-06-01

    Optical access networks are becoming more widespread and the use of multiple services might require a transparent optical network (TON). Multiplexing and privacy could benefit from the combination of wavelength division multiplexing (WDM) and optical coding (OC) and wavelength conversion in optical switches. The routing process needs to be cognizant of different resource types and characteristics such as fiber types, fiber linear impairments such as attenuation, dispersion, etc. as well as fiber nonlinear impairments such as four-wave mixing, cross-phase modulation, etc. Other types of impairments, generated by optical nodes or photonic switches, also affect the signal quality (Q) or the optical signal to noise ratio (OSNR), which is related to the bit error rate (BER). Therefore, both link and switch impairments must be addressed and somehow incorporated into the routing algorithm. However, it is not practical to fully integrate all photonic-specific attributes in the routing process. In this study, new routing parameters and constraints are defined that reflect the distinct characteristics of photonic networking. These constraints are applied to the design phase of TON and expressed as a cost or metric form that will be used in the network routing algorithm.

  10. Changes in perceptions of quality of, and access to, services among clients of a fractional franchise network in Nepal.

    PubMed

    Agha, Sohail; Gage, Anastasia; Balal, Asma

    2007-05-01

    With declining levels of international donor funding for financing reproductive health programmes, developing country governments and international donors are looking towards private sector strategies to expand the supply of quality reproductive health services. One of the challenges of a health franchise is to improve the quality of services provided by independent private practitioners. Private providers are more likely to abide by the quality standards set by a franchiser if they see a financial benefit resulting from franchise participation. This study was conducted to measure whether (a) there were improvements in perceived quality of care and perceived access to health facilities once these facilities became part of a franchise and (b) improvements in perceived quality and perceived access were associated with increased client loyalty to franchised clinics. Franchisees were given basic reproductive health training for seven days and services marketing training for two days. Exit interviews were conducted with male and female clients at health facilities. A pre-test measurement was taken in April 2001, prior to the start of project activities. A post-test measurement was taken in February/March 2002, about 9 months after the pre-test. Multilevel regression analysis, which takes the hierarchical structure of the data into account, was used for the analysis. After taking provider-level variation into account and controlling for client characteristics, the analyses showed significant improvements in perceived quality of care and perceived access to services. Private provider participation in a franchise network helps improve client perceptions of quality of, and access to, services. Improvements in client perceptions of quality and access contribute to increased client loyalty to franchised clinics. Once increased client loyalty translates into higher client volumes, providers are likely to see the benefits of franchise participation. In turn, this should lead to

  11. Ultrahigh-capacity access network architecture for mobile data backhaul using integrated W-band wireless and free-space optical links with OAM multiplexing.

    PubMed

    Fang, Yuan; Yu, Jianjun; Zhang, Junwen; Chi, Nan; Xiao, Jiangnan; Chang, Gee-Kung

    2014-07-15

    In this Letter, we propose and experimentally demonstrate a novel access network architecture using hybrid integrated W-band wireless and free-space optical (FSO) links with orbital angular momentum (OAM) multiplexing. The transmission of a 20 GBd quadrature phase-shift keying signal modulated over 10 OAM modes has been demonstrated over a 0.6 m FSO link and a 0.4 m W-band wireless link at 100 GHz. The experimental results show that the architecture can support future ultrahigh-capacity, converged optical-wireless access networks that require extra bandwidth and system flexibility in mobile data networks.

  12. Creating Electronic Access to Newspaper Information in Nigeria: The Information Aid Network (IFAnet) Experience

    ERIC Educational Resources Information Center

    Ola, Christopher O.; Ojo, Reuben A.

    2006-01-01

    This paper highlights the value of newspaper information and the methods adopted in organizing, preserving and disseminating it. The paper dwells on the traditional ways of managing newspaper resources and the need to device a new medium of accessing the information contents of the resource. It enumerates the steps taken in conserving newspaper…

  13. Four Commandments for Writing Policies for Public-Access Wireless Networks

    ERIC Educational Resources Information Center

    Sauers, Michael

    2006-01-01

    In this article, the author describes what components should be included in a comprehensive policy for public wireless usage in a library. He lists four basic steps, which include: (1) Introduce the service; (2) List the technical requirements; (3) Spell out disclaimers on access, assistance, and liability; and (4) Alert users to security concerns.

  14. Contact North: The Concept, Policy, Development, and Status of the Northern Ontario Distance Education Access Network.

    ERIC Educational Resources Information Center

    Arblaster, John R.

    Contact North/Contact Nord (CN) was designed to enhance distance education opportunities at the secondary and postsecondary levels in Northern Ontario through the use of new information and communication technologies. The central thesis of CN is that access to education at all levels could be improved through a combined effort by community…

  15. Inferential networked ? control with accessibility constraints in both the sensor and actuator channels

    NASA Astrophysics Data System (ADS)

    Peñarrocha, I.; Dolz, D.; Sanchis, R.

    2014-05-01

    The predictor and controller design for an inferential control scheme over a network is addressed. A linear plant with disturbances and measurement noise is assumed to be controlled by a controller that communicates with the sensors and the actuators through a constrained network. An algorithm is proposed such that the scarce available outputs are used to make a prediction of the system evolution with an observer that takes into account the amount of lost data between successful measurements transmissions. The state prediction is then used to calculate the control actions sent to the actuator. The possibility of control action drop due to network constraints is taken into account. This networked control scheme is analysed and both the predictor and controller designs are addressed taking into account the disturbances, the measurement noise, the scarce availability of output samples and the scarce capability of control actions update. The time-varying sampling periods that result for the process inputs and outputs due to network constraints have been determined as a function of the probability of successful transmission on a specified time with a Bernoulli distribution. For both designs ? performance has been established and linear matrix inequality (LMI) design techniques have been used to achieve a numerical solution.

  16. Topical Steroids.

    PubMed

    Oakley, Gretchen M; Harvey, Richard J

    2016-01-01

    Chronic rhinosinusitis with nasal polyps (CRSwNP) is an inflammatory condition with heterogeneous pathophysiology. A cornerstone of the management of this condition is the use of anti-inflammatory agents. Corticosteroids are very effective and the most commonly used, but other drugs with immunodulatory activity such as anti-IL5, doxycycline (Th2), and macrolides (anti-neutrophilic/IL8) have been shown to have efficacy. Although systemic corticosteroids have shown benefit in managing this condition, the frequency of use often required in this condition is associated with significant adverse effects. Topical corticosteroids, particularly when utilized after endoscopic sinus surgery and delivered in a high volume, high pressure manner, provide the desired anti-inflammatory effects with nearly negligible systemic absorption. Studies assessing the long-term use of second generation topical corticosteroids have demonstrated no significant effects on cortisol levels, growth rate, intraocular pressures or lens opacification, or local mucosal atrophy. Patients who often respond most favorably to corticosteroid treatment are those with a Th2-mediated, highly eosinophilic CRSwNP. However, there is a subset of patients who are steroid resistant. In the case of a predominantly neutrophilic CRSwNP, it is important to be aware that patients may respond well to the use of macrolide therapy. Additionally, the use of verapamil has shown promise in increasing steroid responsiveness in a difficult to treat group of patients with steroid resistance. Topical corticosteroids play a key role in the long term management of this complicated inflammatory condition by providing the much needed pharmacologic local control with minimal systemic adverse effects. PMID:27466854

  17. Describing the access network by means of router buffer modelling: a new methodology.

    PubMed

    Sequeira, Luis; Fernández-Navajas, Julián; Saldana, Jose; Gállego, José Ramón; Canales, María

    2014-01-01

    The behaviour of the routers' buffer may affect the quality of service (QoS) of network services under certain conditions, since it may modify some traffic characteristics, as delay or jitter, and may also drop packets. As a consequence, the characterization of the buffer is interesting, especially when multimedia flows are transmitted and even more if they transport information with real-time requirements. This work presents a new methodology with the aim of determining the technical and functional characteristics of real buffers (i.e., behaviour, size, limits, and input and output rate) of a network path. It permits the characterization of intermediate buffers of different devices in a network path across the Internet.

  18. Innovation networks for improving access and quality across the healthcare ecosystem.

    PubMed

    Carroll, Mark; James, Judith A; Lardiere, Michael R; Proser, Michelle; Rhee, Kyu; Sayre, Michael H; Shore, Jay H; Ternullo, Joseph

    2010-01-01

    Partnerships between patient communities, healthcare providers, and academic researchers are key to stepping up the pace and public health impact of clinical and translational research supported by the National Institutes of Health. With emphasis shifting toward community engagement and faster translation of research advances into clinical practice, academic researchers have a vital stake in widening the use of health information technology systems and telehealth networks to support collaboration and innovation. However, limited interaction between academic institutions and healthcare providers hinders the ability to form and sustain the integrated networks that are needed to conduct meaningful community-engaged research that improves public health outcomes. Healthcare providers, especially those affiliated with smaller practices, will need sustainable infrastructure and real incentives to utilize such networks, as well as training and additional resources for ongoing technical assistance. PMID:20043702

  19. Describing the Access Network by means of Router Buffer Modelling: A New Methodology

    PubMed Central

    Fernández-Navajas, Julián; Gállego, José Ramón; Canales, María

    2014-01-01

    The behaviour of the routers' buffer may affect the quality of service (QoS) of network services under certain conditions, since it may modify some traffic characteristics, as delay or jitter, and may also drop packets. As a consequence, the characterization of the buffer is interesting, especially when multimedia flows are transmitted and even more if they transport information with real-time requirements. This work presents a new methodology with the aim of determining the technical and functional characteristics of real buffers (i.e., behaviour, size, limits, and input and output rate) of a network path. It permits the characterization of intermediate buffers of different devices in a network path across the Internet. PMID:25152904

  20. World-wide interactive access to scientific databases via satellite and terrestrial data network

    NASA Technical Reports Server (NTRS)

    Sanderson, T. R.; Albrecht, M. A.; Ciarlo, A.; Brett, M.; Blank, K.; Hughes, P. M. T.; Wallum, G.; Hills, H. K.; Green, J. L.; Mcguire, R. E.; Kamei, T.; Kiplinger, A.; Waite, J. H., Jr.

    1990-01-01

    In order to demonstrate the possibilities for scientific networking and data transfer, a first temporary satellite network link was installed between Czecholovakia and the European space operations center in Darmstadt, during the meeting of the inter-agency consultative group for space science in Prague. Several experiments to show interactive nature of the facility and the capability of the system were carried out, and it was proven that, despite the temporary nature of the installation, the planned demonstrations could be conducted in real time. Demonstrations included electronic mail message, orbit prediction and solar X-ray data. The results of the experiment provided insight into possibilities of data exchange.

  1. 40-Gbit/s photonic random access memory for photonic packet-switched networks

    NASA Astrophysics Data System (ADS)

    Takahashi, Ryo; Nakahara, Tatsushi; Takahata, Kiyoto; Takenouchi, Hirokazu; Yasui, Takako; Kondo, Naoto; Suzuki, Hiroyuki

    2004-06-01

    We present a photonic random access memory (RAM) that can write and read high-speed asynchronous burst optical packets freely by specifying addresses. The photonic RAM consists of an optical clock-pulse generator, an all-optical serial-to-parallel converter, a photonic parallel-to-serial converter, all developed by us, and a CMOS RAM as a storage medium. Unlike conventional optical buffers, which merely function as optical delay lines, the photonic RAM provides various advantages, such as compactness, large capacity, long-term storage, and random access at an arbitrary timing for ultrafast asynchronous burst optical packets. We experimentally confirm its basic operation for 40-Gbit/s 16-bit optical packets.

  2. Synergy Access: A Global Newsletter on Futuristic Communications, Media & Networking. Number 1.

    ERIC Educational Resources Information Center

    Thomas, Wes, Ed.

    A global newsletter on futuristic communications, media and networking is dedicated to creating open, humanistic environments for better interpersonal communication and to exploring the phenomenon of synergy, the coming together of people, ideas and environments for creation of something greater than the sum of the parts. Editorials, poetry, and…

  3. Auxiliary graph based protection for survivable Fiber-Wireless (FiWi) access network considering different levels of failures

    NASA Astrophysics Data System (ADS)

    Liu, Yejun; Guo, Lei; Ma, Rui; Hou, Weigang

    2012-12-01

    Survivability is one of the key issues in Fiber-Wireless (FiWi) access network because network component failures may cause huge data loss, especially when the failures in optical back-end. According to the failure severity, we categorize the failures in optical back-end into two levels, that is, Optical-Network-Unit (ONU)-level failure and segment-level failure. In this paper, instead of the expensive fiber duplication approach traditionally, we propose a novel protection approach for FiWi against ONU-level failure by assigning each ONU several alternate ONUs in the same segment and against the segment-level failure by deploying backup fibers among different segments. On one hand, we optimize the assignment of alternate ONUs, aiming to maximize the amount of protected traffic and minimize the number of wireless hops. On the other hand, we optimize the deployment of backup fibers, aiming to maximize the amount of protected traffic and minimize the length of backup fibers. We mathematically formulate these two objectives as Maximum Protection and Minimum Hops Number (MPMHN) problem and the Maximum Protection and Minimum backup Fibers Length (MPMFL) problem, respectively. An efficient algorithm called Auxiliary Graph based Protection (AGP) is proposed to solve the MPMHN and MPMFL problems. In the simulation, we investigate the performance of AGP in various scenarios and demonstrate the cost-efficiency of the proposed protection approach.

  4. Developing Computer Literacy Skills in Schools with Limited Hub Access.

    ERIC Educational Resources Information Center

    Jay, M. Ellen

    1997-01-01

    Discusses how to meet elementary school student and staff needs for computer access with a hub of networked computers in the library media center. Topics include types of use, including word processing, desktop publishing, curriculum support, and multimedia presentations; scheduling; assigning staff responsibilities; and suggested allocation of…

  5. Low-Power Optical Feeder for VDSL Over Twisted Pair for Last Mile Access Networks

    NASA Astrophysics Data System (ADS)

    Dudley, Sandra E. M.; Quinlan, Terence J.; Henning, Ian D.; Walker, Stuart D.; Davey, Russell P.; Wallace, Andrew D.; Boyd, Ivan; Payne, Dave B.

    2006-01-01

    In this paper, we describe an ultra-low-power optoelectronic very-high-data-rate digital subscriber line (VDSL) system, enabling broadband access to the home over 10 km of optical fiber and 1 km of twisted pair. The cabinet/distribution point interface has a footprint of just 3 × 3 × 1 cm, and consumes only 165 mW. A quadrature-amplitude-modulation (QAM) scheme was used for system tests with 10 Mb/s full duplex achieved, and up to 40-dB up/downstream channel isolation is obtained using hybrid transformers.

  6. Artificial intelligence, neural network, and Internet tool integration in a pathology workstation to improve information access

    NASA Astrophysics Data System (ADS)

    Sargis, J. C.; Gray, W. A.

    1999-03-01

    The APWS allows user friendly access to several legacy systems which would normally each demand domain expertise for proper utilization. The generalized model, including objects, classes, strategies and patterns is presented. The core components of the APWS are the Microsoft Windows 95 Operating System, Oracle, Oracle Power Objects, Artificial Intelligence tools, a medical hyperlibrary and a web site. The paper includes a discussion of how could be automated by taking advantage of the expert system, object oriented programming and intelligent relational database tools within the APWS.

  7. Distributing digital imaging and communications in medicine data and optimizing access over satellite networks.

    PubMed

    Ernst, R D; Kawashima, A; Shepherd, W; Tamm, E P; Sandler, C M

    1999-05-01

    To improve radiology access to full uncompressed Digital Imaging and Communications in Medicine (DICOM) data sets, we evaluated satellite access to a DICOM server. Radiologists' home computers were connected by satellite to a Medweb DICOM server (Medweb, San Francisco, CA). A 10.2-kb data set containing a 19-image head computed tomography (CT) scan was transferred using DirecPC (Hughes Electronics Corp, Arlington, VA) at three different times of the day; 6 AM, 3 PM, and 8 PM. The average transfer time for all 19 images from the DICOM server was 4 minutes and 17 seconds (257 seconds). The slowest transfer rate of 670 seconds (121 kbps) was obtained at 8 PM. The best transfer rate of 2 minutes, 54 seconds (467 kbps) was obtained at 6 AM. The full 16-bit DICOM images were viewed with bone, brain, and soft tissue windows. The Medweb plug-in viewer loaded the first image within 30 seconds of selecting the case for satellite transfer. In conclusion, satellite internet transfer of radiology studies is suitable for timely review of full DICOM data sets and can expand the range of teleradiology consultation.

  8. The International Federation of Digital Seismograph Networks (FDSN): An example of open access to scientific data sharing

    NASA Astrophysics Data System (ADS)

    Suárez, G.; van Eck, T.; Ahern, T.

    2012-04-01

    The International Federation of Digital Seismograph Networks (FDSN) is probably one of the more successful examples of an organization dedicated to the production of data for scientific purposes and its free and open distribution. The FDSN was founded in 1984 with the purpose of: 1. Defining the specifications of digital broadband seismograph systems; 2. Coordinate the siting plans for new observatories in order to obtain optimal global coverage; 3. Develop data formats and protocols to exchange and distribute seismological data; and 4. Establish distributed data centres that provide access to data. The Federation is a non-governmental organization with a Commission status in IASPEI. It is supported and sustained solely by the work and contributions of its affiliates. To date, almost 90 research institutions and seismological networks are members of the FDSN, and FDSN data centers provide data from almost 20,000 seismic observatories distributed worldwide. Of these, more than 200 seismic stations are part of the FDSN backbone network and transmit data in real time. These data transmitted to the data management centres have become the backbone of the rapid determination of earthquake magnitude, location and focal mechanisms, as well as supporting agencies engaged in civil protection and emergency attention. The tsunami warning centres now operating in various oceans are important users of the backbone network. The growth of the data archive in the three distributed national data centres has been exponential since the foundation of the FDSN. Data distribution centres are located in the United States, Europe and Japan. The size of the archive of FDSN-affiliated stations is in the order of 80 Terabytes of data available online. In 2011, one of the FDSN data centres, the Data Management Centre of IRIS distributed more than 162 terabytes of data to scientists and institutions worldwide. The philosophy of open and free access to data produced by high

  9. Placement of Base Stations in Broadband Power Line Communications Access Networks by Means of Multi-criteria Optimization

    NASA Astrophysics Data System (ADS)

    Haidine, Abdelfatteh; Lehnert, Ralf

    Broadband Power Line Communications (B-PLC) technology is an alternative for broadband access networks, allowing bit rates up to currently 200Mbps. This technique uses the wiring of the low-voltage grid in order to offer to the users the telecommunications services, such as Internet, VoIP, VoD, etc. The B-PLC design process is sub-divided into two parts: the Generalized Base Station Placement (GBSP) problem and the PLC Channel Allocation Problem (P-CAP). This paper focuses on GBSP that is modeled as multi-criteria combinatorial optimization problem. Based on our published mathematical modeling, this paper supplies more numerical experiments for the evaluation of Multi-Objective Evolutionary Algorithms (MOEAs) in solving GBSP. Their performance is compared with the single-objective optimization.

  10. Use of the Remote Access Virtual Environment Network (RAVEN) for coordinated IVA-EVA astronaut training and evaluation.

    PubMed

    Cater, J P; Huffman, S D

    1995-01-01

    This paper presents a unique virtual reality training and assessment tool developed under a NASA grant, "Research in Human Factors Aspects of Enhanced Virtual Environments for Extravehicular Activity (EVA) Training and Simulation." The Remote Access Virtual Environment Network (RAVEN) was created to train and evaluate the verbal, mental and physical coordination required between the intravehicular (IVA) astronaut operating the Remote Manipulator System (RMS) arm and the EVA astronaut standing in foot restraints on the end of the RMS. The RAVEN system currently allows the EVA astronaut to approach the Hubble Space Telescope (HST) under control of the IVA astronaut and grasp, remove, and replace the Wide Field Planetary Camera drawer from its location in the HST. Two viewpoints, one stereoscopic and one monoscopic, were created all linked by Ethernet, that provided the two trainees with the appropriate training environments.

  11. Development traumatic brain injury computer user interface for disaster area in Indonesia supported by emergency broadband access network.

    PubMed

    Sutiono, Agung Budi; Suwa, Hirohiko; Ohta, Toshizumi; Arifin, Muh Zafrullah; Kitamura, Yohei; Yoshida, Kazunari; Merdika, Daduk; Qiantori, Andri; Iskandar

    2012-12-01

    Disasters bring consequences of negative impacts on the environment and human life. One of the common cause of critical condition is traumatic brain injury (TBI), namely, epidural (EDH) and subdural hematoma (SDH), due to downfall hard things during earthquake. We proposed and analyzed the user response, namely neurosurgeon, general doctor/surgeon and nurse when they interacted with TBI computer interface. The communication systems was supported by TBI web based applications using emergency broadband access network with tethered balloon and simulated in the field trial to evaluate the coverage area. The interface consisted of demography data and multi tabs for anamnesis, treatment, follow up and teleconference interfaces. The interface allows neurosurgeon, surgeon/general doctors and nurses to entry the EDH and SDH patient's data during referring them on the emergency simulation and evaluated based on time needs and their understanding. The average time needed was obtained after simulated by Lenovo T500 notebook using mouse; 8-10 min for neurosurgeons, 12-15 min for surgeons/general doctors and 15-19 min for nurses. By using Think Pad X201 Tablet, the time needed for entry data was 5-7 min for neurosurgeon, 7-10 min for surgeons/general doctors and 12-16 min for nurses. We observed that the time difference was depending on the computer type and user literacy qualification as well as their understanding on traumatic brain injury, particularly for the nurses. In conclusion, there are five data classification for simply TBI GUI, namely, 1) demography, 2) specific anamnesis for EDH and SDH, 3) treatment action and medicine of TBI, 4) follow up data display and 5) teleneurosurgery for streaming video consultation. The type of computer, particularly tablet PC was more convenient and faster for entry data, compare to that computer mouse touched pad. Emergency broadband access network using tethered balloon is possible to be employed to cover the communications systems in

  12. Development traumatic brain injury computer user interface for disaster area in Indonesia supported by emergency broadband access network.

    PubMed

    Sutiono, Agung Budi; Suwa, Hirohiko; Ohta, Toshizumi; Arifin, Muh Zafrullah; Kitamura, Yohei; Yoshida, Kazunari; Merdika, Daduk; Qiantori, Andri; Iskandar

    2012-12-01

    Disasters bring consequences of negative impacts on the environment and human life. One of the common cause of critical condition is traumatic brain injury (TBI), namely, epidural (EDH) and subdural hematoma (SDH), due to downfall hard things during earthquake. We proposed and analyzed the user response, namely neurosurgeon, general doctor/surgeon and nurse when they interacted with TBI computer interface. The communication systems was supported by TBI web based applications using emergency broadband access network with tethered balloon and simulated in the field trial to evaluate the coverage area. The interface consisted of demography data and multi tabs for anamnesis, treatment, follow up and teleconference interfaces. The interface allows neurosurgeon, surgeon/general doctors and nurses to entry the EDH and SDH patient's data during referring them on the emergency simulation and evaluated based on time needs and their understanding. The average time needed was obtained after simulated by Lenovo T500 notebook using mouse; 8-10 min for neurosurgeons, 12-15 min for surgeons/general doctors and 15-19 min for nurses. By using Think Pad X201 Tablet, the time needed for entry data was 5-7 min for neurosurgeon, 7-10 min for surgeons/general doctors and 12-16 min for nurses. We observed that the time difference was depending on the computer type and user literacy qualification as well as their understanding on traumatic brain injury, particularly for the nurses. In conclusion, there are five data classification for simply TBI GUI, namely, 1) demography, 2) specific anamnesis for EDH and SDH, 3) treatment action and medicine of TBI, 4) follow up data display and 5) teleneurosurgery for streaming video consultation. The type of computer, particularly tablet PC was more convenient and faster for entry data, compare to that computer mouse touched pad. Emergency broadband access network using tethered balloon is possible to be employed to cover the communications systems in

  13. Outline of a multiple-access communication network based on adaptive arrays

    NASA Technical Reports Server (NTRS)

    Zohar, S.

    1982-01-01

    Attention is given to a narrow-band communication system consisting of a central station trying to receive signals simultaneously from K spatially distinct mobile users sharing the same frequencies. One example of such a system is a group of aircraft and ships transmitting messages to a communication satellite. A reasonable approach to such a multiple access system may be based on equipping the central station with an n-element antenna array where n is equal to or greater than K. The array employs K sets of n weights to segregate the signals received from the K users. The weights are determined by direct computation based on position information transmitted by the users. A description is presented of an improved technique which makes it possible to reduce significantly the number of required computer operations in comparison to currently known techniques.

  14. Ultrastable optical frequency dissemination on a multi-access fibre network

    NASA Astrophysics Data System (ADS)

    Bercy, Anthony; Lopez, Olivier; Pottie, Paul-Eric; Amy-Klein, Anne

    2016-07-01

    We report a laboratory demonstration of the dissemination of an ultrastable optical frequency signal to two distant users simultaneously using a branching network. The ultrastable signal is extracted along a main fibre link; it is optically tracked by a narrow linewidth laser diode, which light is injected in a secondary link. The propagation noise of both links is actively compensated. We implement this scheme with two links of 50-km fibre spools, the extraction being set up at the mid-point of the main link. We show that the extracted signal at the end of the secondary link exhibits a fractional frequency instability of 1.4 × 10-15 at 1-s measurement time, almost equal to the 1.3 × 10-15 instability of the main link output end. The long-term instabilities are also very similar, at a level of 3-5 × 10-20 at 3 × 104-s integration time. We also show that the setting up of this extraction device, or of a simpler one, at the main link input, can test the proper functioning of the noise rejection on this main link. This work is a significant step towards a robust and flexible ultrastable network for multi-users dissemination.

  15. Increment of Access Points in Integrated System of Wavelength Division Multiplexed Passive Optical Network Radio over Fiber

    PubMed Central

    Amiri, I. S.; Alavi, S. E.; Soltanian, M. R. K.; Fisal, N.; Supa’at, A. S. M.; Ahmad, H.

    2015-01-01

    This paper describes a novel technique to increase the numbers of access points (APs) in a wavelength division multiplexed-passive optical network (WDM-PON) integrated in a 100 GHz radio-over-fiber (RoF). Eight multi-carriers separated by 25 GHz intervals were generated in the range of 193.025 to 193.200 THz using a microring resonator (MRR) system incorporating an add-drop filter system. All optically generated multi-carriers were utilized in an integrated system of WDM-PON-RoF for transmission of four 43.6 Gb/sec orthogonal frequency division multiplexing (OFDM) signals. Results showed that an acceptable BER variation for different path lengths up to 25 km was achievable for all four access points and thus the transmission of four OFDM channels is feasible for a 25 km standard single mode fiber (SSMF) path length. PMID:26153536

  16. Satellite range delay simulator for a matrix-switched time division multiple-access network simulation system

    NASA Technical Reports Server (NTRS)

    Nagy, Lawrence A.

    1990-01-01

    The Systems Integration, Test, and Evaluation (SITE) facility at NASA Lewis Research Center is presently configured as a satellite-switched time division multiple access (SS-TDMA) network simulator. The purpose of SITE is to demonstrate and evaluate advanced communication satellite technologies, presently embodied by POC components developed under NASA contracts in addition to other hardware, such as ground terminals, designed and built in-house at NASA Lewis. Each ground terminal in a satellite communications system will experience a different aspect of the satellite's motion due mainly to daily tidal effects and station keeping, hence a different duration and rate of variation in the range delay. As a result of this and other effects such as local oscillator instability, each ground terminal must constantly adjust its transmit burst timing so that data bursts from separate ground terminals arrive at the satellite in their assigned time slots, preventing overlap and keeping the system in synchronism. On the receiving end, ground terminals must synchronize their local clocks using reference transmissions received through the satellite link. A feature of the SITE facility is its capability to simulate the varying propagation delays and associated Doppler frequency shifts that the ground terminals in the network have to cope with. Delay is ahcieved by means of two NASA Lewis designed and built range delay simulator (RDS) systems, each independently controlled locally with front panel switches or remotely by an experiment control and monitor (EC/M) computer.

  17. Development of Electronic Resources across Networks in Thailand.

    ERIC Educational Resources Information Center

    Ratchatavorn, Phandao

    2002-01-01

    Discusses the development of electronic resources across library networks in Thailand to meet user needs, particularly electronic journals. Topics include concerns about journal access; limited budgets for library acquisitions of journals; and sharing resources through a centralized database system that allows Web access to journals via Internet…

  18. Novel MDM-PON scheme utilizing self-homodyne detection for high-speed/capacity access networks.

    PubMed

    Chen, Yuanxiang; Li, Juhao; Zhu, Paikun; Wu, Zhongying; Zhou, Peng; Tian, Yu; Ren, Fang; Yu, Jinyi; Ge, Dawei; Chen, Jingbiao; He, Yongqi; Chen, Zhangyuan

    2015-12-14

    In this paper, we propose a cost-effective, energy-saving mode-division-multiplexing passive optical network (MDM-PON) scheme utilizing self-homodyne detection for high-speed/capacity access network based on low modal-crosstalk few-mode fiber (FMF) and all-fiber mode multiplexer/demultiplexer (MUX/DEMUX). In the proposed scheme, one of the spatial modes is used to transmit a portion of signal carrier (namely pilot-tone) as the local oscillator (LO), while the others are used for signal-bearing channels. At the receiver, the pilot-tone and the signal can be separated without strong crosstalk and sent to the receiver for coherent detection. The spectral efficiency (SE) is significantly enhanced when multiple spatial channels are used. Meanwhile, the self-homodyne detection scheme can effectively suppress laser phase noise, which relaxes the requirement for the lasers line-width at the optical line terminal or optical network units (OLT/ONUs). The digital signal processing (DSP) at the receiver is also simplified since it removes the need for frequency offset compensation and complex phase correction, which reduces the computational complexity and energy consumption. Polarization division multiplexing (PDM) that offers doubled SE is also supported by the scheme. The proposed scheme is scalable to multi-wavelength application when wavelength MUX/DEMUX is utilized. Utilizing the proposed scheme, we demonstrate a proof of concept 4 × 40-Gb/s orthogonal frequency division multiplexing (OFDM) transmission over 55-km FMF using low modal-crosstalk two-mode FMF and MUX/DEMUX with error free operation. Compared with back to back case, less than 1-dB Q-factor penalty is observed after 55-km FMF of the four channels. Signal power and pilot-tone power are also optimized to achieve the optimal transmission performance. PMID:26698996

  19. Energy-Efficiency Analysis of a Distributed Queuing Medium Access Control Protocol for Biomedical Wireless Sensor Networks in Saturation Conditions

    PubMed Central

    Otal, Begonya; Alonso, Luis; Verikoukis, Christos

    2011-01-01

    The aging population and the high quality of life expectations in our society lead to the need of more efficient and affordable healthcare solutions. For this reason, this paper aims for the optimization of Medium Access Control (MAC) protocols for biomedical wireless sensor networks or wireless Body Sensor Networks (BSNs). The hereby presented schemes always have in mind the efficient management of channel resources and the overall minimization of sensors’ energy consumption in order to prolong sensors’ battery life. The fact that the IEEE 802.15.4 MAC does not fully satisfy BSN requirements highlights the need for the design of new scalable MAC solutions, which guarantee low-power consumption to the maximum number of body sensors in high density areas (i.e., in saturation conditions). In order to emphasize IEEE 802.15.4 MAC limitations, this article presents a detailed overview of this de facto standard for Wireless Sensor Networks (WSNs), which serves as a link for the introduction and initial description of our here proposed Distributed Queuing (DQ) MAC protocol for BSN scenarios. Within this framework, an extensive DQ MAC energy-consumption analysis in saturation conditions is presented to be able to evaluate its performance in relation to IEEE 802.5.4 MAC in highly dense BSNs. The obtained results show that the proposed scheme outperforms IEEE 802.15.4 MAC in average energy consumption per information bit, thus providing a better overall performance that scales appropriately to BSNs under high traffic conditions. These benefits are obtained by eliminating back-off periods and collisions in data packet transmissions, while minimizing the control overhead. PMID:22319351

  20. The Network for the Improvement of Addiction Treatment (NIATx): Enhancing Access and Retention**

    PubMed Central

    McCarty, Dennis; Gustafson, David H.; Wisdom, Jennifer P.; Ford, Jay; Choi, Dongseok; Molfenter, Todd; Capoccia, Victor; Cotter, Frances

    2007-01-01

    The Network for the Improvement of Addiction Treatment (NIATx) teaches participating treatment centers to use process improvement strategies. A cross-site evaluation monitored impacts on days between first contact and first treatment and percent of patients who started treatment and completed two, three and four units of care (i.e., one outpatient session, one day of intensive outpatient care, and one week of residential treatment). The analysis included 13 agencies that began participation in August 2003, submitted 10 to 15 months of data, and attempted improvements in outpatient (n = 7), intensive outpatient (n = 4) or residential treatment services (n = 4) (two agencies provided data for two levels of care). Days to treatment declined 37% (from 19.6 to 12.4 days) across levels of care; the change was significant overall and for outpatient and intensive outpatient services. Significant overall improvement in retention in care was observed for the second unit of care (72% to 85%; 18% increase) and the third unit of care (62% to 73%; 17% increase); when level of care was assessed, a significant gain was found only for intensive outpatient services. Small incremental changes in treatment processes can lead to significant reductions in days to treatment and consistent gains in retention. PMID:17129680

  1. Improving the prediction accuracy of residue solvent accessibility and real-value backbone torsion angles of proteins by guided-learning through a two-layer neural network.

    PubMed

    Faraggi, Eshel; Xue, Bin; Zhou, Yaoqi

    2009-03-01

    This article attempts to increase the prediction accuracy of residue solvent accessibility and real-value backbone torsion angles of proteins through improved learning. Most methods developed for improving the backpropagation algorithm of artificial neural networks are limited to small neural networks. Here, we introduce a guided-learning method suitable for networks of any size. The method employs a part of the weights for guiding and the other part for training and optimization. We demonstrate this technique by predicting residue solvent accessibility and real-value backbone torsion angles of proteins. In this application, the guiding factor is designed to satisfy the intuitive condition that for most residues, the contribution of a residue to the structural properties of another residue is smaller for greater separation in the protein-sequence distance between the two residues. We show that the guided-learning method makes a 2-4% reduction in 10-fold cross-validated mean absolute errors (MAE) for predicting residue solvent accessibility and backbone torsion angles, regardless of the size of database, the number of hidden layers and the size of input windows. This together with introduction of two-layer neural network with a bipolar activation function leads to a new method that has a MAE of 0.11 for residue solvent accessibility, 36 degrees for psi, and 22 degrees for phi. The method is available as a Real-SPINE 3.0 server in http://sparks.informatics.iupui.edu.

  2. 47 CFR 27.16 - Network access requirements for Block C in the 746-757 and 776-787 MHz bands.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Network access requirements for Block C in the 746-757 and 776-787 MHz bands. 27.16 Section 27.16 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Applications and...

  3. 47 CFR 27.16 - Network access requirements for Block C in the 746-757 and 776-787 MHz bands.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 2 2014-10-01 2014-10-01 false Network access requirements for Block C in the 746-757 and 776-787 MHz bands. 27.16 Section 27.16 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Applications and...

  4. 47 CFR 27.16 - Network access requirements for Block C in the 746-757 and 776-787 MHz bands.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Network access requirements for Block C in the 746-757 and 776-787 MHz bands. 27.16 Section 27.16 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Applications and...

  5. 47 CFR 27.16 - Network access requirements for Block C in the 746-757 and 776-787 MHz bands.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Network access requirements for Block C in the 746-757 and 776-787 MHz bands. 27.16 Section 27.16 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Applications and...

  6. DISTRIBUTED STRUCTURE-SEARCHABLE TOXICITY (DSSTOX) DATABASE NETWORK: MAKING PUBLIC TOXICITY DATA RESOURCES MORE ACCESSIBLE AND USABLE FOR DATA EXPLORATION AND SAR DEVELOPMENT

    EPA Science Inventory


    Distributed Structure-Searchable Toxicity (DSSTox) Database Network: Making Public Toxicity Data Resources More Accessible and U sable for Data Exploration and SAR Development

    Many sources of public toxicity data are not currently linked to chemical structure, are not ...

  7. Open Access Alternatives

    ERIC Educational Resources Information Center

    Tenopir, Carol

    2004-01-01

    Open access publishing is a hot topic today. But open access publishing can have many different definitions, and pros and cons vary with the definitions. Open access publishing is especially attractive to companies and small colleges or universities that are likely to have many more readers than authors. A downside is that a membership fee sounds…

  8. A scheduling-function-based distributed access protocol that uses CDM to relay control information in a network with hidden nodes

    SciTech Connect

    Gold, Y.I.; Franta, W.R.

    1987-05-01

    The authors introduce a method for broadcasting control information (such as the information essential for correct operation of SOSAM and other scheduling-function-based access protocols) in stationary networks with ''hidden'' nodes (multihop networks). Control information is transmitted as short bit-parallel control messages on a separate control channel whose capacity is shared among the bits of a control message using code division multiplexing (CDM). The CDM method takes advantage of spread-spectrum signal properties that allow, in particular, high accuracy of time-of-arrival measurement and relatively easy separation of multipath copies of a control message. Generalized versions of SOSAM's scheduling function and the protocol algorithm are also provided. The generalized protocol, which applies the new method for broadcasting control information, provides distributed collision-free channel-access control, and allows prioritized access with high channel utilization and small expected message delay.

  9. Novel wavelength division multiplex-radio over fiber-passive optical network architecture for multiple access points based on multitone generation and triple sextupling frequency

    NASA Astrophysics Data System (ADS)

    Cheng, Guangming; Guo, Banghong; Liu, Songhao; Huang, Xuguang

    2014-01-01

    An innovative wavelength division multiplex-radio over fiber-passive optical network architecture for multiple access points (AP) based on multitone generation and triple sextupling frequency is proposed and demonstrated. A dual-drive Mach-Zehnder modulator (DD-MZM) is utilized to realize the multitone generation. Even sidebands are suppressed to make the adjacent frequency separation twice the frequency of the local oscillator by adjusting the modulation voltage of the DD-MZM. Due to adopting three fiber Bragg gratings to reflect the unmodulated sidebands for uplink communications source free at optical network unit (ONU), is achieved. The system can support at least three APs at one ONU simultaneously with a 30 km single-mode fiber (SMF) transmission and 5 Gb/s data rate both for uplink and downlink communications. The theoretical analysis and simulation results show the architecture has an excellent performance and will be a promising candidate in future hybrid access networks.

  10. Structuring waveguide-grating-based wavelength-division multiplexing/optical code division multiple access network codecs over topology of concentric circles

    NASA Astrophysics Data System (ADS)

    Huang, Jen-Fa; Nieh, Ta-Chun; Chen, Kai-Sheng

    2013-01-01

    The cyclic period and free spectral range of arrayed-waveguide gratings (AWG) in a wavelength-division multiplexing/optical code division multiple access optical code division multiple access network are exploited. The total optical network unit (ONU) of network capacity is partitioned into groups of different wavelength in accordance with the geographical location of subscribers based on the radial distance of the ONU to the optical line terminal. Combining concentric circles round by round for ONU groups enables a fixed round-trip time in the data transmission and a significant increase in system performance. Using AWG router, the proposed topology of concentric circles retains signature orthogonality and minimizes wavelength collisions on the photo-detector. Furthermore, the adoption of extended M-sequence codes corresponding to the AWG codec provides a simpler, more efficient coding procedure and accommodates more users in a single group.

  11. Providing Access to CD-ROM Databases in a Campus Setting. Part II: Networking CD-ROMs via a LAN.

    ERIC Educational Resources Information Center

    Koren, Judy

    1992-01-01

    The second part of a report on CD-ROM networking in libraries describes LAN (local area network) technology; networking software and towers; gateway software for connecting to campuswide networks; Macintosh LANs; and network licenses. Several product and software reviews are included, and a sidebar lists vendor addresses. (NRP)

  12. Full-Duplex Link Providing Alternative Wired and Wireless Broadband Access for the Wavelength-Division Multiplexing Passive Optical Network with a Uniform Converged Signal Format

    NASA Astrophysics Data System (ADS)

    Ma, Jianxin

    2014-05-01

    A full-duplex link implementing alternative wired and wireless access for wavelength-division multiplexing passive optical network is proposed with the uniformed three-tone converged optical signal, which provides a wired or wireless downlink access signal alternatively and an uplink optical carrier. The uplink optical carrier reversed by the converged optical signal makes the hybrid optical node unit free from the optical source. The simulation results show that the full-duplex link with a 10-Gb/s 16-quadrature amplitude modulation (16-QAM) downstream and 5 Gb/s binary upstream can provide both wired access with a bit-error rate below 10-9 and radio-over-fiber-based wireless access with a bit-error rate below 10-7 over 40 km of fiber without an optical source and optical amplifier in the hybrid optical node unit.

  13. Digital dual-rate burst-mode receiver for 10G and 1G coexistence in optical access networks

    NASA Astrophysics Data System (ADS)

    Delgado Mendinueta, José Manuel; Mitchell, John E.; Bayvel, Polina; Thomsen, Benn C.

    2011-07-01

    A digital dual-rate burst-mode receiver, intended to support 10 and 1 Gb/s coexistence in optical access networks, is proposed and experimentally characterized. The receiver employs a standard DC-coupled photoreceiver followed by a 20 GS/s digitizer and the detection of the packet presence and line-rate is implemented in the digital domain. A polyphase, 2 samples-per-bit digital signal processing algorithm is then used for efficient clock and data recovery of the 10/1.25 Gb/s packets. The receiver performance is characterized in terms of sensitivity and dynamic range under burst-mode operation for 10/1.25 Gb/s intensity modulated data in terms of both the packet error rate (PER) and the payload bit error rate (pBER). The impact of packet preamble lengths of 16, 32, 48, and 64 bits, at 10 Gb/s, on the receiver performance is investigated. We show that there is a trade-off between pBER and PER that is limited by electrical noise and digitizer clipping at low and high received powers, respectively, and that a 16/2-bit preamble at 10/1.25 Gb/s is sufficient to reliably detect packets at both line-rates over a burst-to-burst dynamic range of 14,5dB with a sensitivity of -18.5dBm at 10 Gb/s.

  14. Digital dual-rate burst-mode receiver for 10G and 1G coexistence in optical access networks.

    PubMed

    Mendinueta, José Manuel Delgado; Mitchell, John E; Bayvel, Polina; Thomsen, Benn C

    2011-07-18

    A digital dual-rate burst-mode receiver, intended to support 10 and 1 Gb/s coexistence in optical access networks, is proposed and experimentally characterized. The receiver employs a standard DC-coupled photoreceiver followed by a 20 GS/s digitizer and the detection of the packet presence and line-rate is implemented in the digital domain. A polyphase, 2 samples-per-bit digital signal processing algorithm is then used for efficient clock and data recovery of the 10/1.25 Gb/s packets. The receiver performance is characterized in terms of sensitivity and dynamic range under burst-mode operation for 10/1.25 Gb/s intensity modulated data in terms of both the packet error rate (PER) and the payload bit error rate (pBER). The impact of packet preamble lengths of 16, 32, 48, and 64 bits, at 10 Gb/s, on the receiver performance is investigated. We show that there is a trade-off between pBER and PER that is limited by electrical noise and digitizer clipping at low and high received powers, respectively, and that a 16/2-bit preamble at 10/1.25 Gb/s is sufficient to reliably detect packets at both line-rates over a burst-to-burst dynamic range of 14,5 dB with a sensitivity of -18.5 dBm at 10 Gb/s. PMID:21934767

  15. Beyond Access. Diversity and Opportunity in Higher Education. Proceedings of the Annual European Access Network (EAN) Convention (5th, Amsterdam, The Netherlands, July 1-3, 1996).

    ERIC Educational Resources Information Center

    de Bie, Marloes, Ed.; Derks, Bas, Ed.; Suikjer, Firiel, Ed.

    This proceedings presents papers given at a 1996 European conference on access to higher education. Following two introductory papers are the following 13 plenary session papers: "A European Perspective" (James Wimberley); "An American Perspective--Diversity in American Higher Education and U.S. Federal Policy" (Tom Wolanin); "An Eastern European…

  16. The Cornell/Xerox Commission on Preservation and Access Joint Study in Digital Preservation. Report: Phase 1 (January 1990-December 1991). Digital Capture, Paper Facsimiles, and Network Access.

    ERIC Educational Resources Information Center

    Kenney, Anne R.; Personius, Lynne K.

    The primary emphasis of this study of the use of digital technology to preserve library materials was the capture of brittle books as digital images and the production of printed paper facsimiles. Of equal interest, however, was the role of digital technology in providing access to library resources, and preliminary work in this area has also been…

  17. Biotech in medicine--the topic of the Olten Meeting 2010.

    PubMed

    Heinzelmann, Elsbeth

    2011-01-01

    Since 1998, the biotechnet--the national network of competence in biotech research--has been helping partners from industry to access excellence in R&D, giving them optimal support at low cost. Its annual 'Olten Meeting' is a dynamic hub for companies and research institutes as it highlights the latest trends in biotech. On November 24, 2010, the topical subject was biotech in medicine.

  18. Building capacity for the assessment of HIV drug resistance: experiences from the PharmAccess African Studies to Evaluate Resistance network.

    PubMed

    Hamers, Raph L; Straatsma, Elske; Kityo, Cissy; Wallis, Carole L; Stevens, Wendy S; Sigaloff, Kim C E; Siwale, Margaret; Conradie, Francesca; Botes, Mariette E; Mandaliya, Kishor; Wellington, Maureen; Osibogun, Akin; van Vugt, Michèle; Rinke de Wit, Tobias F

    2012-05-01

    The PharmAccess African Studies to Evaluate Resistance (PASER) network was established as a collaborative partnership of clinical sites, laboratories, and research groups in 6 African countries; its purpose is to build research and laboratory capacity in support of a coordinated effort to assess population-level acquired and transmitted human immunodeficiency virus type-1 drug resistance (HIVDR), thus contributing to the goals of the World Health Organization Global HIV Drug Resistance Network. PASER disseminates information to medical professionals and policy makers and conducts observational research related to HIVDR. The sustainability of the network is challenged by funding limitations, constraints in human resources, a vulnerable general health infrastructure, and high cost and complexity of molecular diagnostic testing. This report highlights experiences and challenges in the PASER network from 2006 to 2010. PMID:22544185

  19. Analysis and Benchmark of Hydrological Network Representation Models for Improved Access and Query in Web-based System

    NASA Astrophysics Data System (ADS)

    Demir, I.; Szczepanek, R.

    2015-12-01

    Web based systems allow users to delineate watersheds on interactive map environments using server side processing and databases. With increasing resolution of hydrological networks, optimized methods for storage of network representation in databases, and efficient queries and actions on the river network structure become critical. This presentation provides a comprehensive study on analysis of network models in relational databases for hydrological networks, and benchmarking common queries and operations on the network structure using these methods. The analysis has been applied to the hydrological network of the State of Iowa based on 90m DEM consist of 600,000 network nodes. The application results indicate that certain representation methods provide massive improvements on query times and storage of network structure in the database. Suggested method allows watershed delineation tools running on the client-side with desktop-like performance. This will allow users to carry out large scale analysis and visualizations tasks on the web.

  20. Design and implementation of flexible TWDM-PON with PtP WDM overlay based on WSS for next-generation optical access networks

    NASA Astrophysics Data System (ADS)

    Wu, Bin; Yin, Hongxi; Qin, Jie; Liu, Chang; Liu, Anliang; Shao, Qi; Xu, Xiaoguang

    2016-09-01

    Aiming at the increasing demand of the diversification services and flexible bandwidth allocation of the future access networks, a flexible passive optical network (PON) scheme combining time and wavelength division multiplexing (TWDM) with point-to-point wavelength division multiplexing (PtP WDM) overlay is proposed for the next-generation optical access networks in this paper. A novel software-defined optical distribution network (ODN) structure is designed based on wavelength selective switches (WSS), which can implement wavelength and bandwidth dynamical allocations and suits for the bursty traffic. The experimental results reveal that the TWDM-PON can provide 40 Gb/s downstream and 10 Gb/s upstream data transmission, while the PtP WDM-PON can support 10 GHz point-to-point dedicated bandwidth as the overlay complement system. The wavelengths of the TWDM-PON and PtP WDM-PON are allocated dynamically based on WSS, which verifies the feasibility of the proposed structure.

  1. Multi-channel multi-radio using 802.11 based media access for sink nodes in wireless sensor networks.

    PubMed

    Campbell, Carlene E-A; Khan, Shafiullah; Singh, Dhananjay; Loo, Kok-Keong

    2011-01-01

    The next generation surveillance and multimedia systems will become increasingly deployed as wireless sensor networks in order to monitor parks, public places and for business usage. The convergence of data and telecommunication over IP-based networks has paved the way for wireless networks. Functions are becoming more intertwined by the compelling force of innovation and technology. For example, many closed-circuit TV premises surveillance systems now rely on transmitting their images and data over IP networks instead of standalone video circuits. These systems will increase their reliability in the future on wireless networks and on IEEE 802.11 networks. However, due to limited non-overlapping channels, delay, and congestion there will be problems at sink nodes. In this paper we provide necessary conditions to verify the feasibility of round robin technique in these networks at the sink nodes by using a technique to regulate multi-radio multichannel assignment. We demonstrate through simulations that dynamic channel assignment scheme using multi-radio, and multichannel configuration at a single sink node can perform close to optimal on the average while multiple sink node assignment also performs well. The methods proposed in this paper can be a valuable tool for network designers in planning network deployment and for optimizing different performance objectives.

  2. Multi-Channel Multi-Radio Using 802.11 Based Media Access for Sink Nodes in Wireless Sensor Networks

    PubMed Central

    Campbell, Carlene E.-A.; Khan, Shafiullah; Singh, Dhananjay; Loo, Kok-Keong

    2011-01-01

    The next generation surveillance and multimedia systems will become increasingly deployed as wireless sensor networks in order to monitor parks, public places and for business usage. The convergence of data and telecommunication over IP-based networks has paved the way for wireless networks. Functions are becoming more intertwined by the compelling force of innovation and technology. For example, many closed-circuit TV premises surveillance systems now rely on transmitting their images and data over IP networks instead of standalone video circuits. These systems will increase their reliability in the future on wireless networks and on IEEE 802.11 networks. However, due to limited non-overlapping channels, delay, and congestion there will be problems at sink nodes. In this paper we provide necessary conditions to verify the feasibility of round robin technique in these networks at the sink nodes by using a technique to regulate multi-radio multichannel assignment. We demonstrate through simulations that dynamic channel assignment scheme using multi-radio, and multichannel configuration at a single sink node can perform close to optimal on the average while multiple sink node assignment also performs well. The methods proposed in this paper can be a valuable tool for network designers in planning network deployment and for optimizing different performance objectives. PMID:22163883

  3. Network unites payers, physicians, hospitals. System participants work together to improve access to care and to design cost-saving incentives.

    PubMed

    Cassidy, J

    1993-05-01

    Through Sacred Heart Health System (SHHS), Eugene, OR, physicians, payers, and hospitals are designing a network that will integrate care and improve access by reducing healthcare costs. Together, system members design cost-saving incentives and the products the system offers the community. They promote managed care as the most efficient means to coordinate care and reduce costs. All participants share in the risks of a capitated payment system. Since the system pulled together the payers, physician groups, and hospitals, many of these entities' management functions were consolidated at the system level to avoid duplication and reduce administrative costs. Bringing in physicians was the most difficult yet important aspect of forming a successful network. Working with two physician groups in the community, the system's sponsor-the Sisters of St. Joseph of Peace, Health and Hospital Services-developed the Physician Practice Board. The board, representing 300 physicians, meets weekly and makes recommendations on issues that affect physicians. SHHS also added innovative new functions such as an integrated medical cost management and continuous quality improvement program. Another key to success is a clinically oriented information system, which will allow the system to track patients once they leave the hospital. It also will provide a better understanding of what things have an impact on outcomes and will reduce paperwork. A portion of the system's revenue is designated for initiatives to improve access. And the system recently appointed a tack force on access to explore what they can do in cooperation with others in the community. PMID:10125358

  4. Freshman Health Topics

    ERIC Educational Resources Information Center

    Hovde, Karen

    2011-01-01

    This article examines a cluster of health topics that are frequently selected by students in lower division classes. Topics address issues relating to addictive substances, including alcohol and tobacco, eating disorders, obesity, and dieting. Analysis of the topics examines their interrelationships and organization in the reference literature.…

  5. A novel PON based UMTS broadband wireless access network architecture with an algorithm to guarantee end to end QoS

    NASA Astrophysics Data System (ADS)

    Sana, Ajaz; Hussain, Shahab; Ali, Mohammed A.; Ahmed, Samir

    2007-09-01

    In this paper we proposes a novel Passive Optical Network (PON) based broadband wireless access network architecture to provide multimedia services (video telephony, video streaming, mobile TV, mobile emails etc) to mobile users. In the conventional wireless access networks, the base stations (Node B) and Radio Network Controllers (RNC) are connected by point to point T1/E1 lines (Iub interface). The T1/E1 lines are expensive and add up to operating costs. Also the resources (transceivers and T1/E1) are designed for peak hours traffic, so most of the time the dedicated resources are idle and wasted. Further more the T1/E1 lines are not capable of supporting bandwidth (BW) required by next generation wireless multimedia services proposed by High Speed Packet Access (HSPA, Rel.5) for Universal Mobile Telecommunications System (UMTS) and Evolution Data only (EV-DO) for Code Division Multiple Access 2000 (CDMA2000). The proposed PON based back haul can provide Giga bit data rates and Iub interface can be dynamically shared by Node Bs. The BW is dynamically allocated and the unused BW from lightly loaded Node Bs is assigned to heavily loaded Node Bs. We also propose a novel algorithm to provide end to end Quality of Service (QoS) (between RNC and user equipment).The algorithm provides QoS bounds in the wired domain as well as in wireless domain with compensation for wireless link errors. Because of the air interface there can be certain times when the user equipment (UE) is unable to communicate with Node B (usually referred to as link error). Since the link errors are bursty and location dependent. For a proposed approach, the scheduler at the Node B maps priorities and weights for QoS into wireless MAC. The compensations for errored links is provided by the swapping of services between the active users and the user data is divided into flows, with flows allowed to lag or lead. The algorithm guarantees (1)delay and throughput for error-free flows,(2)short term fairness

  6. Suppression of optical beat interference-noise in orthogonal frequency division multiple access-passive optical network link using self-homodyne balanced detection

    NASA Astrophysics Data System (ADS)

    Won, Yong-Yuk; Jung, Sang-Min; Han, Sang-Kook

    2014-08-01

    A new technique, which reduces optical beat interference (OBI) noise in orthogonal frequency division multiple access-passive optical network (OFDMA-PON) links, is proposed. A self-homodyne balanced detection, which uses a single laser for the optical line terminal (OLT) as well as for the optical network unit (ONU), reduces OBI noise and also improves the signal to noise ratio (SNR) of the discrete multi-tone (DMT) signal. The proposed scheme is verified by transmitting quadrature phase shift keying (QPSK)-modulated DMT signal over a 20-km single mode fiber. The optical signal to noise ratio (OSNR), that is required for BER of 10-5, is reduced by 2 dB in the balanced detection compared with a single channel due to the cancellation of OBI noise in conjunction with the local laser.

  7. A Wide Dynamics and Fast Scan Interrogating Method for a Fiber Bragg Grating Sensor Network Implemented Using Code Division Multiple Access

    PubMed Central

    Kim, Youngbok; Jeon, Sie-Wook; Kwon, Won-Bae; Park, Chang-Soo

    2012-01-01

    We propose and demonstrate a fiber Bragg grating (FBG) sensor network employing the code division multiple access (CDMA) technique to identify information from individual sensors. To detect information without considering time delays between sensors, a sliding correlation method is applied, in which two different signals with the same pseudo-random binary sequence (PRBS) pattern, but slightly different frequencies, are applied to the source and detector sides. Moreover, for time domain detection, a wavelength-to-time conversion technique using a wavelength dispersive medium is introduced. The experimental results show that the proposed sensor network has a wide strain dynamic range of 2,400 με and a low crosstalk of 950:1. PMID:22778619

  8. Physical-layer energy-efficient receiving method based on selective sampling in orthogonal frequency division multiplexing access passive optical network

    NASA Astrophysics Data System (ADS)

    Li, Jun; He, Hao; Bi, Meihua; Hu, Weisheng

    2014-05-01

    We propose a physical-layer energy-efficient receiving method based on selective sampling in an orthogonal frequency division multiplexing access passive optical network (OFDMA-PON). By using the special designed frame head, the receiver within an optical network unit (ONU) can identify the destination of the incoming frame. The receiver only samples at the time when the destination is in agreement with the ONU, while it stays in standby during the rest of the time. We clarify its feasibility through an experiment and analyze the downstream traffic delay by simulation. The results indicate that under limited delay conditions, ˜60% energy can be saved compared with the traditional receiving method in the OFDMA-PON system with 512 ONUs.

  9. A wide dynamics and fast scan interrogating method for a fiber Bragg grating sensor network implemented using code division multiple access.

    PubMed

    Kim, Youngbok; Jeon, Sie-Wook; Kwon, Won-Bae; Park, Chang-Soo

    2012-01-01

    We propose and demonstrate a fiber Bragg grating (FBG) sensor network employing the code division multiple access (CDMA) technique to identify information from individual sensors. To detect information without considering time delays between sensors, a sliding correlation method is applied, in which two different signals with the same pseudo-random binary sequence (PRBS) pattern, but slightly different frequencies, are applied to the source and detector sides. Moreover, for time domain detection, a wavelength-to-time conversion technique using a wavelength dispersive medium is introduced. The experimental results show that the proposed sensor network has a wide strain dynamic range of 2,400 με and a low crosstalk of 950:1.

  10. ICSW2AN : An Inter-vehicle Communication System Using Mobile Access Point over Wireless Wide Area Networks

    NASA Astrophysics Data System (ADS)

    Byun, Tae-Young

    This paper presents a prototype of inter-vehicle communication system using mobile access point that internetworks wired or wireless LAN and wireless WAN anywhere. Implemented mobile access point can be equipped with various wireless WAN interfaces such as WCDMA and HSDPA. Mobile access point in the IP mechanism has to process connection setup procedure to one wireless WAN. To show the applicability of the mobile access point to inter-vehicle communication, a simplified V2I2V-based car communication system called ICSW2AN is implemented to evaluate major performance metrics by road test. In addition, results of road test for traffic information service are investigated in view of RTT, latency and server processing time. The experimental result indicates that V2I2V-based car communication system sufficiently can provide time-tolerant traffic information to moving vehicles while more than two mobile devices in restricted spaces such as car, train and ship access wireless Internet simultaneously.

  11. Channel Access in Erlang

    SciTech Connect

    Nicklaus, Dennis J.

    2013-10-13

    We have developed an Erlang language implementation of the Channel Access protocol. Included are low-level functions for encoding and decoding Channel Access protocol network packets as well as higher level functions for monitoring or setting EPICS process variables. This provides access to EPICS process variables for the Fermilab Acnet control system via our Erlang-based front-end architecture without having to interface to C/C++ programs and libraries. Erlang is a functional programming language originally developed for real-time telecommunications applications. Its network programming features and list management functions make it particularly well-suited for the task of managing multiple Channel Access circuits and PV monitors.

  12. Compounded Topical Analgesics for Chronic Pain.

    PubMed

    Cline, Abigail E; Turrentine, Jake E

    2016-01-01

    Analgesic medications compounded for topical use are gaining popularity for the management of chronic pain. The advantages of topical pain medications include reduction of systemic adverse effects, improved patient acceptance, few drug interactions, ease of dose determination, avoidance of first-pass metabolism, and direct access to the target site. Compounded topical medications typically use a mixture of 3 or more single medications to achieve multiple complementary effects at lower doses of each individual medication. Herein, we review the mechanisms, adverse effects, and evidence for some of the most commonly used medications in topical compounds for pain management. Because more topical medications are used for chronic pain, dermatologists can expect an increase in irritant and allergic contact dermatitis related to these medications. PMID:27649348

  13. Improving access to health information for older migrants by using grounded theory and social network analysis to understand their information behaviour and digital technology use.

    PubMed

    Goodall, K T; Newman, L A; Ward, P R

    2014-11-01

    Migrant well-being can be strongly influenced by the migration experience and subsequent degree of mainstream language acquisition. There is little research on how older Culturally And Linguistically Diverse (CALD) migrants who have 'aged in place' find health information, and the role which digital technology plays in this. Although the research for this paper was not focused on cancer, we draw out implications for providing cancer-related information to this group. We interviewed 54 participants (14 men and 40 women) aged 63-94 years, who were born in Italy or Greece, and who migrated to Australia mostly as young adults after World War II. Constructivist grounded theory and social network analysis were used for data analysis. Participants identified doctors, adult children, local television, spouse, local newspaper and radio as the most important information sources. They did not generally use computers, the Internet or mobile phones to access information. Literacy in their birth language, and the degree of proficiency in understanding and using English, influenced the range of information sources accessed and the means used. The ways in which older CALD migrants seek and access information has important implications for how professionals and policymakers deliver relevant information to them about cancer prevention, screening, support and treatment, particularly as information and resources are moved online as part of e-health.

  14. Improving access to health information for older migrants by using grounded theory and social network analysis to understand their information behaviour and digital technology use.

    PubMed

    Goodall, K T; Newman, L A; Ward, P R

    2014-11-01

    Migrant well-being can be strongly influenced by the migration experience and subsequent degree of mainstream language acquisition. There is little research on how older Culturally And Linguistically Diverse (CALD) migrants who have 'aged in place' find health information, and the role which digital technology plays in this. Although the research for this paper was not focused on cancer, we draw out implications for providing cancer-related information to this group. We interviewed 54 participants (14 men and 40 women) aged 63-94 years, who were born in Italy or Greece, and who migrated to Australia mostly as young adults after World War II. Constructivist grounded theory and social network analysis were used for data analysis. Participants identified doctors, adult children, local television, spouse, local newspaper and radio as the most important information sources. They did not generally use computers, the Internet or mobile phones to access information. Literacy in their birth language, and the degree of proficiency in understanding and using English, influenced the range of information sources accessed and the means used. The ways in which older CALD migrants seek and access information has important implications for how professionals and policymakers deliver relevant information to them about cancer prevention, screening, support and treatment, particularly as information and resources are moved online as part of e-health. PMID:25250535

  15. Science and Technology Undergraduate Students' Use of the Internet, Cell Phones and Social Networking Sites to Access Library Information

    ERIC Educational Resources Information Center

    Salisbury, Lutishoor; Laincz, Jozef; Smith, Jeremy J.

    2012-01-01

    Many academic libraries and publishers have developed mobile-optimized versions of their web sites and catalogs. Almost all database vendors and major journal publishers have provided a way to connect to their resources via the Internet and the mobile web. In light of this pervasive use of the Internet, mobile devices and social networking, this…

  16. [Topical therapy of rosacea].

    PubMed

    Schöfer, H

    2013-07-01

    Metronidazole and azelaic acid are the only topical medications approved for rosacea. All other topical treatments for rosacea and its special forms are used off-label. Topical steroids are not indicated in rosacea, because of their side effects (induction of steroid rosacea, high risk of facial skin atrophy, and high risk of rebound after cessation of therapy). Topical as well as systemic steroids are allowed only as initial and short term therapy for acute forms of rosacea (e.g. rosacea fulminans). Papular and pustular rosacea is the major indication for topical therapy. Sebaceous gland and connective tissue hyperplasia in glandular-hypertrophic rosacea as well as erythema in erythematous rosacea do not respond well to topical measures. A new active substance, the alpha-2-adrenoreceptor agonist brimonidine, will be approved soon for the topical treatment of erythema in rosacea. All severe forms of rosacea should initially be treated with a combination of topical and systemic agents. After improvement of the clinical symptoms, topical treatment alone is usually adequate to maintain the control.

  17. PREFACE: CEWQO Topical Issue CEWQO Topical Issue

    NASA Astrophysics Data System (ADS)

    Bozic, Mirjana; Man'ko, Margarita

    2009-09-01

    This topical issue of Physica Scripta collects selected peer-reviewed contributions based on invited and contributed talks and posters presented at the 15th Central European Workshop on Quantum Optics (CEWQO) which took place in Belgrade 29 May-3 June 2008 (http://cewqo08.phy.bg.ac.yu). On behalf of the whole community took place in Belgrade 29 May-3 June 2008 (http://cewqo08.phy.bg.ac.yu, cewqo08.phy.bg.ac.yu). On behalf of the whole community of the workshop, we thank the referees for their careful reading and useful suggestions which helped to improve all of the submitted papers. A brief description of CEWQO The Central European Workshop on Quantum Optics is a series of conferences started informally in Budapest in 1992. Sometimes small events transform into important conferences, as in the case of CEWQO. Professor Jozsef Janszky, from the Research Institute of Solid State Physics and Optics, is the founder of this series. Margarita Man'ko obtained the following information from Jozsef Janszky during her visit to Budapest, within the framework of cooperation between the Russian and Hungarian Academies of Sciences in 2005. He organized a small workshop on quantum optics in Budapest in 1992 with John Klauder as a main speaker. Then, bearing in mind that a year before Janszky himself was invited by Vladimir Buzek to give a seminar on the same topic in Bratislava, he decided to assign the name 'Central European Workshop on Quantum Optics', considering the seminar in Bratislava to be the first workshop and the one in Budapest the second. The third formal workshop took place in Bratislava in 1993 organized by Vladimir Buzek, then in 1994 (Budapest, by Jozsef Janszky), 1995 and 1996 (Budmerice, Slovakia, by Vladimir Buzek), 1997 (Prague, by Igor Jex), 1999 (Olomouc, Czech Republic, by Zdenek Hradil), 2000 (Balatonfüred, Hungary, by Jozsef Janszky ), 2001 (Prague, by Igor Jex), 2002 (Szeged, Hungary, by Mihaly Benedict), 2003 (Rostock,Germany, by Werner Vogel and

  18. Demonstrations of 10 and 40 Gbps upstream transmissions using 1.2 GHz RSOA-based ONU in long-reach access networks

    NASA Astrophysics Data System (ADS)

    Yeh, C. H.; Chow, C. W.; Wu, Y. F.; Chen, H. Y.

    2012-03-01

    Carrier-distributed long-reach passive optical network (LR-PON) is a promising candidate for future access networks. In this work, we analyze and compare the 4 × 2.5 Gb/s and 4 × 10 Gb/s upstream traffics in a carrier-distributed LR-PON using four wavelength-multiplexed 2.5 Gb/s on-off keying (OOK) and 10 Gb/s optical orthogonal frequency division multiplexing-quadrature amplitude modulation (OFDM-QAM) signals. Four commercial 1.2 GHz bandwidth reflective semiconductor optical amplifiers (RSOAs) are used in each optical networking unit (ONU) for the generation of the upstream signal. Due to the limited bandwidth of the RSOA, only up to 2.5 Gb/s upstream OOK signal can be generated. However, by using the spectral efficient modulation, such as OFDM-QAM, 10 Gb/s data rate can be achieved. 20, 50 and 75 km fiber transmissions are also compared using the two different kinds of modulation respectively.

  19. Salicylic Acid Topical

    MedlinePlus

    ... skin blemishes in people who have acne. Topical salicylic acid is also used to treat skin conditions that involve scaling or overgrowth of skin ... water for 15 minutes.Do not apply topical salicylic acid to skin that is broken, red, swollen, irritated, or infected. ...

  20. Creating collaboration opportunities for marine research across the Arctic: The SEARCH-ACCESS partnership and an emerging sea ice prediction research network

    NASA Astrophysics Data System (ADS)

    Eicken, H.; Bitz, C. M.; Gascard, J.; Kaminski, T.; Karcher, M. J.; Kauker, F.; Overland, J. E.; Stroeve, J. C.; Wiggins, H. V.

    2013-12-01

    Rapid Arctic environmental and socio-economic change presents major challenges and opportunities to Arctic residents, government agencies and the private sector. The Arctic Ocean and its ice cover, in particular, are in the midst of transformative change, ranging from declines in sea-ice thickness and summer ice extent to threats to coastal communities and increases in maritime traffic and offshore resource development. The US interagency Study of Environmental Arctic Change (SEARCH) and the European Arctic Climate Change, Economy and Society (ACCESS) project are addressing both scientific research needs and stakeholder information priorities to improve understanding and responses to Arctic change. Capacity building, coordination and integration of activities at the international level and across sectors and stakeholder groups are major challenges that have to be met. ACCESS and SEARCH build on long-standing collaborations with a focus on environmental change in the Arctic ocean-ice-atmosphere system and the most pressing research needs to inform marine policy, resource management and threats to Arctic coastal communities. To illustrate the approach, key results and major conclusions from this international coordination and collaboration effort, we focus on a nascent sea-ice prediction research network. This activity builds on the Arctic Sea Ice Outlook that was initiated by SEARCH and the European DAMOCLES project (a precursor to ACCESS) and has now grown into an international community of practice that synthesizes, evaluates and discusses sea-ice predictions on seasonal to interannual scales. Key goals of the effort which is now entering into a new phase include the comparative evaluation of different prediction approaches, including the combination of different techniques, the compilation of reference datasets and model output, guidance on the design and implementation of observing system efforts to improve predictions and information transfer into private

  1. Network Basics.

    ERIC Educational Resources Information Center

    Tennant, Roy

    1992-01-01

    Explains how users can find and access information resources available on the Internet. Highlights include network information centers (NICs); lists, both formal and informal; computer networking protocols, including international standards; electronic mail; remote log-in; and file transfer. (LRW)

  2. Itch Management: Topical Agents.

    PubMed

    Metz, Martin; Staubach, Petra

    2016-01-01

    Chronic pruritus is a common problem in patients with inflammatory skin diseases as well as in subjects with dry or sensitive skin. Regardless of the underlying cause of the pruritus, a topical therapy is not only useful but most often necessary to achieve symptom control. A good topical therapy should fulfill different functions. An optimal basic therapy based on the condition of the skin is important to repair epithelial barrier defects and to rehydrate the skin. An adequate disease-specific topical therapy is crucial for inflamed skin, e.g. anti-inflammatory topical therapy is an important part in the treatment of atopic dermatitis. Finally, the use of specific antipruritic substances can help to improve pruritus in patients irrespective of the underlying disease. Here, we summarize topical agents used in the treatment of chronic pruritus. PMID:27578070

  3. On-the-field performance of quintuple-play long-reach OFDM-based WDM-PON optical access networks.

    PubMed

    Llorente, Roberto; Morant, Maria; Pellicer, Eloy; Herman, Milan; Nagy, Zsolt; Alves, Tiago; Cartaxo, Adolfo; Herrera, Javier; Correcher, Jose; Quinlan, Terence; Walker, Stuart; Rodrigues, Cláudio; Cluzeaud, Pierre; Schmidt, Axel; Piesiewicz, Radoslaw; Sambaraju, Rakesh

    2014-03-24

    In this paper the on-the-field performance of a WDM-PON optical access providing quintuple-play services using orthogonal frequency division multiplexing (OFDM) modulation is evaluated in a real fiber-to-the-home (FTTH) network deployed by Towercom operator in Bratislava (Slovakia). A bundle of quintuple-play services comprising full-standard OFDM-based signals (LTE, WiMAX, UWB and DVB-T) and an ad-hoc OFDM-GbE signal is transmitted in coexistence per single user. Both downstream and upstream transmission performances are evaluated in different on-the-field long-reach optical link distance configurations. Four wavelength multi-user transmission of quintuple-play OFDM services is demonstrated exceeding 60.8 km reach in standard single mode fiber. PMID:24663968

  4. 1 Gbps full-duplex links for ultra-dense-WDM 6.25 GHz frequency slots in optical metro-access networks.

    PubMed

    Altabas, Jose A; Izquierdo, David; Lazaro, Jose A; Lerin, Adolfo; Sotelo, Felix; Garces, Ignacio

    2016-01-11

    1 Gbps full-duplex optical links for 6.25 GHz ultra dense WDM frequency slots are demonstrated and optimized for cost-effective metro-access networks. The OLT-ONU downlinks are based on 1 Gbps Nyquist-DPSK using MZM and single-detector heterodyne reception obtaining a sensitivity of -52 dBm. The ONU-OLT uplinks are based on 1 Gbps NRZ-DPSK by directly phase modulated DFB and also single-detector heterodyne reception obtaining same sensitivity of -52 dBm. The power budget of full-duplex link is 43 dB. These proposed links can provide service to 16 (32) users at each 100 (200) GHz WDM channel.

  5. Experimental demonstration of wavelength domain rogue-free ONU based on wavelength-pairing for TDM/WDM optical access networks.

    PubMed

    Lee, Jie Hyun; Park, Heuk; Kang, Sae-Kyoung; Lee, Joon Ki; Chung, Hwan Seok

    2015-11-30

    In this study, we propose and experimentally demonstrate a wavelength domain rogue-free ONU based on wavelength-pairing of downstream and upstream signals for time/wavelength division-multiplexed optical access networks. The wavelength-pairing tunable filter is aligned to the upstream wavelength channel by aligning it to one of the downstream wavelength channels. Wavelength-pairing is implemented with a compact and cyclic Si-AWG integrated with a Ge-PD. The pairing filter covered four 100 GHz-spaced wavelength channels. The feasibility of the wavelength domain rogue-free operation is investigated by emulating malfunction of the misaligned laser. The wavelength-pairing tunable filter based on the Si-AWG blocks the upstream signal in the non-assigned wavelength channel before data collision with other ONUs.

  6. On-the-field performance of quintuple-play long-reach OFDM-based WDM-PON optical access networks.

    PubMed

    Llorente, Roberto; Morant, Maria; Pellicer, Eloy; Herman, Milan; Nagy, Zsolt; Alves, Tiago; Cartaxo, Adolfo; Herrera, Javier; Correcher, Jose; Quinlan, Terence; Walker, Stuart; Rodrigues, Cláudio; Cluzeaud, Pierre; Schmidt, Axel; Piesiewicz, Radoslaw; Sambaraju, Rakesh

    2014-03-24

    In this paper the on-the-field performance of a WDM-PON optical access providing quintuple-play services using orthogonal frequency division multiplexing (OFDM) modulation is evaluated in a real fiber-to-the-home (FTTH) network deployed by Towercom operator in Bratislava (Slovakia). A bundle of quintuple-play services comprising full-standard OFDM-based signals (LTE, WiMAX, UWB and DVB-T) and an ad-hoc OFDM-GbE signal is transmitted in coexistence per single user. Both downstream and upstream transmission performances are evaluated in different on-the-field long-reach optical link distance configurations. Four wavelength multi-user transmission of quintuple-play OFDM services is demonstrated exceeding 60.8 km reach in standard single mode fiber.

  7. Topical diclofenac solution.

    PubMed

    Moen, Marit D

    2009-01-01

    Topical diclofenac solution (Pennsaid) is a liquid formulation containing the NSAID diclofenac sodium (1.5% w/w). The solution base contains 45% w/w dimethyl sulfoxide (DMSO) to enhance the absorption of diclofenac through the skin. Topical diclofenac solution is applied directly to the knee for treatment of symptoms associated with osteoarthritis of the knee. In well designed 4- to 12-week trials in patients with primary osteoarthritis of the knee, topical diclofenac solution (40 drops four times daily) was significantly more effective than placebo or vehicle control (carrier solution without diclofenac) for improving Western Ontario and McMaster Universities (WOMAC) Osteoarthritis Index pain and physical function, and improving patient global assessment (PGA) and/or patient overall health assessment scores from baseline to the final assessments. Topical diclofenac solution (50 drops three times daily) was as effective as oral diclofenac 150 mg/day for improving WOMAC pain and physical function and PGA scores in a 12-week double-blind study in patients with osteoarthritis of the knee. Topical diclofenac solution was generally well tolerated. The most common treatment-emergent adverse event experienced by topical diclofenac solution recipients was dry skin at the application site. Gastrointestinal adverse events and abnormal laboratory parameters were less common with topical diclofenac solution than with oral diclofenac. PMID:19943711

  8. Topical diclofenac solution.

    PubMed

    Moen, Marit D

    2009-01-01

    Topical diclofenac solution (Pennsaid) is a liquid formulation containing the NSAID diclofenac sodium (1.5% w/w). The solution base contains 45% w/w dimethyl sulfoxide (DMSO) to enhance the absorption of diclofenac through the skin. Topical diclofenac solution is applied directly to the knee for treatment of symptoms associated with osteoarthritis of the knee. In well designed 4- to 12-week trials in patients with primary osteoarthritis of the knee, topical diclofenac solution (40 drops four times daily) was significantly more effective than placebo or vehicle control (carrier solution without diclofenac) for improving Western Ontario and McMaster Universities (WOMAC) Osteoarthritis Index pain and physical function, and improving patient global assessment (PGA) and/or patient overall health assessment scores from baseline to the final assessments. Topical diclofenac solution (50 drops three times daily) was as effective as oral diclofenac 150 mg/day for improving WOMAC pain and physical function and PGA scores in a 12-week double-blind study in patients with osteoarthritis of the knee. Topical diclofenac solution was generally well tolerated. The most common treatment-emergent adverse event experienced by topical diclofenac solution recipients was dry skin at the application site. Gastrointestinal adverse events and abnormal laboratory parameters were less common with topical diclofenac solution than with oral diclofenac.

  9. Advances in Navy pharmacy information technology: accessing Micromedex via the Composite Healthcare Computer System and local area networks.

    PubMed

    Koerner, S D; Becker, F

    1999-07-01

    The pharmacy profession has long used technology to more effectively bring health care to the patient. Navy pharmacy has embraced technology advances in its daily operations, from computers to dispensing robots. Evolving from the traditional role of compounding and dispensing specialists, pharmacists are establishing themselves as vital team members in direct patient care: on the ward, in ambulatory clinics, in specialty clinics, and in other specialty patient care programs (e.g., smoking cessation). An important part of the evolution is the timely access to the most up-to-date information available. Micromedex, Inc. (Denver, Colorado), has developed a number of computer CD-ROM-based full-text pharmacy, toxicology, emergency medicine, and patient education products. Micromedex is a recognized leader with regard to total pharmaceutical information availability. This article discusses the implementation of Micromedex products within the established Composite Healthcare Computer System and the subsequent use by and effect on the international Navy pharmacy community.

  10. Using single side-band modulation for colorless OFDM-WDM access network to alleviate Rayleigh backscattering effects.

    PubMed

    Yeh, Chien-Hung; Chow, Chi-Wai

    2016-05-16

    In this investigation, we demonstrate a new colorless orthogonal-frequency-division-multiplexing (OFDM) wavelength-division-multiplexing passive optical network (WDM-PON) system with Rayleigh backscattering (RB) noise mitigation. Here, only a single laser source at the central office (CO) is needed to produce the downstream signal and distributed continuous-wave (CW) carrier, which will then be modulated at the optical networking unit (ONU) to produce the upstream signal. Single side-band (SSB) modulation is used to wavelength-shift the distributed CW carrier, which will be launched into a reflective semiconductor optical amplifier (RSOA) based ONU for directly modulation of 5.15 Gbps OFDM upstream signal. To avoid the radio-frequency (RF) power fading and chromatic fiber dispersion, the four-band OFDM modulation is proposed to generate a 40 Gbps downstream when a Mach-Zehnder modulator (MZM) with -0.7 chirp parameter is used. Hence, the RB circumvention can be centralized in the CO. Moreover, the signal performances of downstream and upstream are also studied and discussed in this measurement.

  11. Using single side-band modulation for colorless OFDM-WDM access network to alleviate Rayleigh backscattering effects.

    PubMed

    Yeh, Chien-Hung; Chow, Chi-Wai

    2016-05-16

    In this investigation, we demonstrate a new colorless orthogonal-frequency-division-multiplexing (OFDM) wavelength-division-multiplexing passive optical network (WDM-PON) system with Rayleigh backscattering (RB) noise mitigation. Here, only a single laser source at the central office (CO) is needed to produce the downstream signal and distributed continuous-wave (CW) carrier, which will then be modulated at the optical networking unit (ONU) to produce the upstream signal. Single side-band (SSB) modulation is used to wavelength-shift the distributed CW carrier, which will be launched into a reflective semiconductor optical amplifier (RSOA) based ONU for directly modulation of 5.15 Gbps OFDM upstream signal. To avoid the radio-frequency (RF) power fading and chromatic fiber dispersion, the four-band OFDM modulation is proposed to generate a 40 Gbps downstream when a Mach-Zehnder modulator (MZM) with -0.7 chirp parameter is used. Hence, the RB circumvention can be centralized in the CO. Moreover, the signal performances of downstream and upstream are also studied and discussed in this measurement. PMID:27409910

  12. Climate Literacy and Energy Awareness Network releases search widget

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2011-11-01

    The Climate Literacy and Energy Awareness Network (CLEAN) has launched a widget that can be embedded in any Web site to search the network's catalog of online resources relating to climate and energy topics for students in grades 6-12 and for general audiences. The catalog includes more than 300 high-quality existing digital resources, including learning activities, videos, visualizations, and short investigations that have been reviewed and annotated for scientific accuracy and pedagogical potential. The widget allows users to search keywords and then access the full catalog record of resources from the search. The CLEAN Web site includes a section on teaching climate and energy topics.

  13. mobile Digital Access to a Web-enhanced Network (mDAWN): Assessing the Feasibility of Mobile Health Tools for Self-Management of Type-2 Diabetes.

    PubMed

    Ho, Kendall; Newton, Lana; Boothe, Allison; Novak-Lauscher, Helen

    2015-01-01

    The mobile Digital Access to a Web-enhanced Network (mDAWN) program was implemented as an online, mobile self-management system to support patients with type-2 diabetes and their informal caregivers. Patients used wireless physiological sensors, received text messages, and had access to a secure web platform with health resources and semi-facilitated discussion forum. Outcomes were evaluated using (1) pre and post self-reported health behavior measures, (2) physiological outcomes, (3) program cost, and (4) in-depth participant interviews. The group had significantly decreased health distress, HbA1c levels, and systolic blood pressure. Participants largely saw the mDAWN as providing good value for the costs involved and found the program to be empowering in gaining control over their diabetes. mHealth programs have the potential to improve clinical outcomes through cost effective patient-led care for chronic illness. Further evaluation needs to examine integration of similar mHealth programs into the patient-physician relationship.

  14. Informatics in radiology: integration of the medical imaging resource center into a teaching hospital network to allow single sign-on access.

    PubMed

    Prevedello, Luciano M; Andriole, Katherine P; Khorasani, Ryan Roobian Ramin

    2009-01-01

    The RSNA Medical Imaging Resource Center (MIRC) software is an open-source program that allows users to identify, index, and retrieve images, teaching files, and other radiologic data that share a common underlying structure. The software is being continually improved as new challenges and different needs become apparent. Although version T30 is easily installed on a stand-alone computer, its implementation at healthcare enterprises with complex network architecture may be challenging with respect to security because users cannot log on by using a standard enterprise-wide authentication protocol. Instead, authentication takes place through the local MIRC database, creating security concerns and potential organizational problems. In this setting, the Lightweight Directory Access Protocol (LDAP) can be used to provide a single sign-on environment and increase authentication security. A commercial directory service using LDAP has been successfully integrated with MIRC in a large multifacility enterprise to provide single sign-on capability compatible with the institutional networking policies for password security.

  15. Delay guaranteed VoD services over group-based integrated fiber-wireless (FiWi) access networks with energy efficiency

    NASA Astrophysics Data System (ADS)

    Li, Yan; Dai, Shifang; Chang, Xiangmao

    2015-08-01

    In group-based fiber-wireless (FiWi) access networks, where wireless clients are divided into several groups according to their interested Internet services, VoD services will meet new challenges considering the diversity of video requesting probability for each wireless group. In this paper, we categorize wireless groups into "video-hot" group with great interest in VoD services and "video-cold" group with infrequent video requesting. For video requests from "video-hot" groups, we firstly propose an energy-efficient optical network unit (ONU) selection approach to reduce ONU power consumption by selecting a subset of ONUs to support such requests, then our previously proposed rebroadcast and patching scheme can be effectively applied. For video requests from "video-cold" groups, a batched multicasting scheme is presented for energy and bandwidth saving. Both of the VoD schemes mentioned in this study are with the aim to minimize worst-case playback delay (WPD) which is particularly important as Internet users. In view of that some ONUs may need to handle video requests from two kinds of group, optimal ONU channel assignment aims to minimize weighted overall WPD is also studied. The efficiency of the work is finally demonstrated by the simulations.

  16. [Access to health services: approaches, concepts, policies and analysis model].

    PubMed

    Assis, Marluce Maria Araújo; de Jesus, Washington Luiz Abreu

    2012-11-01

    Access to health services is a multifaceted and multidimensional issue involving political, economic, social, organizational, technical and symbolic aspects in establishing access to universal healthcare. This theoretical review paper intends to discuss the different approaches, analyze the context and policies for special groups on access, marking an analysis model delineated by the above aspects, from readings on the topic in question. This analysis reveals a diversity of approaches to access the formulation and implementation of public policies and their potential for changing the organization of the health system. We identified progress in reducing inequalities in health and increased access to the network of the Unified Health System (SUS), especially in primary care. There were also limitations related to accessibility, fragmentation, decentralization and regionalization of the service network, with inadequacies in the process of care and attention to specific groups, and regional disparities. Finally, the analysis model proposed seeks to develop a critical stance to reflect and intervene in health practices and services, with the objective goal being responsible, comprehensive, effective, equitable and quality healthcare.

  17. Women's Health Topics

    MedlinePlus

    ... Women's Health 10903 New Hampshire Avenue WO32-2333 Silver Spring, MD 20993 More in Women's Health Topics ... Food and Drug Administration 10903 New Hampshire Avenue Silver Spring, MD 20993 1-888-INFO-FDA (1- ...

  18. 76 FR 56091 - Expansion of 911 Access; Telecommunications Loan Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-12

    ... that enables access to a seamless, nationwide telecommunications network. With access to the same advanced telecommunications networks as its urban counterparts, especially broadband networks designed to..., ``Department Programs and Activities Excluded from Executive Order 12372'' (50 FR 47034)....

  19. Conversion of perhydropolysilazane into a SiOx network triggered by vacuum ultraviolet irradiation: access to flexible, transparent barrier coatings.

    PubMed

    Prager, Lutz; Dierdorf, Andreas; Liebe, Hubert; Naumov, Sergej; Stojanović, Sandra; Heller, Roswitha; Wennrich, Luise; Buchmeiser, Michael R

    2007-01-01

    The photochemical conversion of 200-500 nm layers of perhydropolysilazane --(SiH2-NH)n-- (PHPS) in the presence of oxygen into an SiOx network was studied. Different UV sources in the wavelength range of 160-240 nm, that is, 172 nm Xe2* and 222 nm KrCl* excimer, and 185 nm Hg low-pressure (HgLP) lamps were used for these purposes. The role of both ozone and O(1D) as well as of catalytic amounts of tertiary amines in the degradation process of PHPS and the formation of SiOx were studied. In this context, the kinetics of the entire reaction were elucidated and allowed both a continuous and discontinuous process to be established for the production of fully transparent, flexible barrier coatings. Barrier improvement factors (BIFs) of 400 were achieved with one single layer on 23 microm poly(ethyleneterephthalate) (PET), which translated into oxygen transmission rates (OTRs) of 0.20 cm3 m(-2) day(-1) bar(-1). Double layers prepared by this technique allowed the realization of OTRs of or=800.

  20. IP Internal Movement and Topicalization

    ERIC Educational Resources Information Center

    Kuo, Pei-Jung

    2009-01-01

    In this dissertation, I investigate the phenomenon of internal topicalization cross-linguistically, using Chinese as a starting point. Internal topicalization refers to constructions in which a topic phrase is placed between the subject and the verb (in contrast to external topicalization, which involves a topic in the CP domain). I argue that…

  1. An ultra low-power and traffic-adaptive medium access control protocol for wireless body area network.

    PubMed

    Ullah, Sana; Kwak, Kyung Sup

    2012-06-01

    Wireless Body Area Network (WBAN) consists of low-power, miniaturized, and autonomous wireless sensor nodes that enable physicians to remotely monitor vital signs of patients and provide real-time feedback with medical diagnosis and consultations. It is the most reliable and cheaper way to take care of patients suffering from chronic diseases such as asthma, diabetes and cardiovascular diseases. Some of the most important attributes of WBAN is low-power consumption and delay. This can be achieved by introducing flexible duty cycling techniques on the energy constraint sensor nodes. Stated otherwise, low duty cycle nodes should not receive frequent synchronization and control packets if they have no data to send/receive. In this paper, we introduce a Traffic-adaptive MAC protocol (TaMAC) by taking into account the traffic information of the sensor nodes. The protocol dynamically adjusts the duty cycle of the sensor nodes according to their traffic-patterns, thus solving the idle listening and overhearing problems. The traffic-patterns of all sensor nodes are organized and maintained by the coordinator. The TaMAC protocol is supported by a wakeup radio that is used to accommodate emergency and on-demand events in a reliable manner. The wakeup radio uses a separate control channel along with the data channel and therefore it has considerably low power consumption requirements. Analytical expressions are derived to analyze and compare the performance of the TaMAC protocol with the well-known beacon-enabled IEEE 802.15.4 MAC, WiseMAC, and SMAC protocols. The analytical derivations are further validated by simulation results. It is shown that the TaMAC protocol outperforms all other protocols in terms of power consumption and delay.

  2. PREFACE: CEWQO Topical Issue CEWQO Topical Issue

    NASA Astrophysics Data System (ADS)

    Bozic, Mirjana; Man'ko, Margarita

    2009-09-01

    This topical issue of Physica Scripta collects selected peer-reviewed contributions based on invited and contributed talks and posters presented at the 15th Central European Workshop on Quantum Optics (CEWQO) which took place in Belgrade 29 May-3 June 2008 (http://cewqo08.phy.bg.ac.yu). On behalf of the whole community took place in Belgrade 29 May-3 June 2008 (http://cewqo08.phy.bg.ac.yu, cewqo08.phy.bg.ac.yu). On behalf of the whole community of the workshop, we thank the referees for their careful reading and useful suggestions which helped to improve all of the submitted papers. A brief description of CEWQO The Central European Workshop on Quantum Optics is a series of conferences started informally in Budapest in 1992. Sometimes small events transform into important conferences, as in the case of CEWQO. Professor Jozsef Janszky, from the Research Institute of Solid State Physics and Optics, is the founder of this series. Margarita Man'ko obtained the following information from Jozsef Janszky during her visit to Budapest, within the framework of cooperation between the Russian and Hungarian Academies of Sciences in 2005. He organized a small workshop on quantum optics in Budapest in 1992 with John Klauder as a main speaker. Then, bearing in mind that a year before Janszky himself was invited by Vladimir Buzek to give a seminar on the same topic in Bratislava, he decided to assign the name 'Central European Workshop on Quantum Optics', considering the seminar in Bratislava to be the first workshop and the one in Budapest the second. The third formal workshop took place in Bratislava in 1993 organized by Vladimir Buzek, then in 1994 (Budapest, by Jozsef Janszky), 1995 and 1996 (Budmerice, Slovakia, by Vladimir Buzek), 1997 (Prague, by Igor Jex), 1999 (Olomouc, Czech Republic, by Zdenek Hradil), 2000 (Balatonfüred, Hungary, by Jozsef Janszky ), 2001 (Prague, by Igor Jex), 2002 (Szeged, Hungary, by Mihaly Benedict), 2003 (Rostock,Germany, by Werner Vogel and

  3. Network of Research Infrastructures for European Seismology (NERIES) - Web Portal Developments for Interactive Access to Earthquake Data on a European Scale

    NASA Astrophysics Data System (ADS)

    Spinuso, A.; Trani, L.; Rives, S.; Thomy, P.; Euchner, F.; Schorlemmer, D.; Saul, J.; Heinloo, A.; Bossu, R.; van Eck, T.

    2008-12-01

    The Network of Research Infrastructures for European Seismology (NERIES) is European Commission (EC) project whose focus is networking together seismological observatories and research institutes into one integrated European infrastructure that provides access to data and data products for research. Seismological institutes and organizations in European and Mediterranean countries maintain large, geographically distributed data archives, therefore this scenario suggested a design approach based on the concept of an internet service oriented architecture (SOA) to establish a cyberinfrastructure for distributed and heterogeneous data streams and services. Moreover, one of the goals of NERIES is to design and develop a Web portal that acts as the uppermost layer of the infrastructure and provides rendering capabilities for the underlying sets of data The Web services that are currently being designed and implemented will deliver data that has been adopted to appropriate formats. The parametric information about a seismic event is delivered using a seismology- specific Extensible mark-up Language(XML) format called QuakeML (https://quake.ethz.ch/quakeml), which has been formalized and implemented in coordination with global earthquake-information agencies. Uniform Resource Identifiers (URIs) are used to assign identifiers to (1) seismic-event parameters described by QuakeML, and (2) generic resources, for example, authorities, locations providers, location methods, software adopted, and so on, described by use of a data model constructed with the resource description framework (RDF) and accessible as a service. The European-Mediterranean Seismological Center (EMSC) has implemented a unique event identifier (UNID) that will create the seismic event URI used by the QuakeML data model. Access to data such as broadband waveform, accelerometric data and stations inventories will be also provided through a set of Web services that will wrap the middleware used by the

  4. Network of Research Infrastructures for European Seismology (NERIES)-Web Portal Developments for Interactive Access to Earthquake Data on a European Scale

    NASA Astrophysics Data System (ADS)

    Spinuso, A.; Trani, L.; Rives, S.; Thomy, P.; Euchner, F.; Schorlemmer, D.; Saul, J.; Heinloo, A.; Bossu, R.; van Eck, T.

    2009-04-01

    The Network of Research Infrastructures for European Seismology (NERIES) is European Commission (EC) project whose focus is networking together seismological observatories and research institutes into one integrated European infrastructure that provides access to data and data products for research. Seismological institutes and organizations in European and Mediterranean countries maintain large, geographically distributed data archives, therefore this scenario suggested a design approach based on the concept of an internet service oriented architecture (SOA) to establish a cyberinfrastructure for distributed and heterogeneous data streams and services. Moreover, one of the goals of NERIES is to design and develop a Web portal that acts as the uppermost layer of the infrastructure and provides rendering capabilities for the underlying sets of data The Web services that are currently being designed and implemented will deliver data that has been adopted to appropriate formats. The parametric information about a seismic event is delivered using a seismology-specific Extensible mark-up Language(XML) format called QuakeML (https://quake.ethz.ch/quakeml), which has been formalized and implemented in coordination with global earthquake-information agencies. Uniform Resource Identifiers (URIs) are used to assign identifiers to (1) seismic-event parameters described by QuakeML, and (2) generic resources, for example, authorities, locations providers, location methods, software adopted, and so on, described by use of a data model constructed with the resource description framework (RDF) and accessible as a service. The European-Mediterranean Seismological Center (EMSC) has implemented a unique event identifier (UNID) that will create the seismic event URI used by the QuakeML data model. Access to data such as broadband waveform, accelerometric data and stations inventories will be also provided through a set of Web services that will wrap the middleware used by the

  5. Workshop on neural networks

    SciTech Connect

    Uhrig, R.E.; Emrich, M.L.

    1990-01-01

    The topics covered in this report are: Learning, Memory, and Artificial Neural Systems; Emerging Neural Network Technology; Neural Networks; Digital Signal Processing and Neural Networks; Application of Neural Networks to In-Core Fuel Management; Neural Networks in Process Control; Neural Network Applications in Image Processing; Neural Networks for Multi-Sensor Information Fusion; Neural Network Research in Instruments Controls Division; Neural Networks Research in the ORNL Engineering Physics and Mathematics Division; Neural Network Applications for Linear Programming; Neural Network Applications to Signal Processing and Diagnostics; Neural Networks in Filtering and Control; Neural Network Research at Tennessee Technological University; and Global Minima within the Hopfield Hypercube.

  6. An orthogonal wavelet division multiple-access processor architecture for LTE-advanced wireless/radio-over-fiber systems over heterogeneous networks

    NASA Astrophysics Data System (ADS)

    Mahapatra, Chinmaya; Leung, Victor CM; Stouraitis, Thanos

    2014-12-01

    The increase in internet traffic, number of users, and availability of mobile devices poses a challenge to wireless technologies. In long-term evolution (LTE) advanced system, heterogeneous networks (HetNet) using centralized coordinated multipoint (CoMP) transmitting radio over optical fibers (LTE A-ROF) have provided a feasible way of satisfying user demands. In this paper, an orthogonal wavelet division multiple-access (OWDMA) processor architecture is proposed, which is shown to be better suited to LTE advanced systems as compared to orthogonal frequency division multiple access (OFDMA) as in LTE systems 3GPP rel.8 (3GPP, http://www.3gpp.org/DynaReport/36300.htm). ROF systems are a viable alternative to satisfy large data demands; hence, the performance in ROF systems is also evaluated. To validate the architecture, the circuit is designed and synthesized on a Xilinx vertex-6 field-programmable gate array (FPGA). The synthesis results show that the circuit performs with a clock period as short as 7.036 ns (i.e., a maximum clock frequency of 142.13 MHz) for transform size of 512. A pipelined version of the architecture reduces the power consumption by approximately 89%. We compare our architecture with similar available architectures for resource utilization and timing and provide performance comparison with OFDMA systems for various quality metrics of communication systems. The OWDMA architecture is found to perform better than OFDMA for bit error rate (BER) performance versus signal-to-noise ratio (SNR) in wireless channel as well as ROF media. It also gives higher throughput and mitigates the bad effect of peak-to-average-power ratio (PAPR).

  7. Topical Therapies for Pruritus

    PubMed Central

    Elmariah, Sarina B.; Lerner, Ethan A.

    2011-01-01

    Itch, or pruritus, is the predominant symptom associated with acute and chronic cutaneous disease and in some cases, may be debilitating. To date, there is no single universally effective anti-itch treatment. As the pathophysiology of itch in most cutaneous or systemic disorders remains unclear, anti-pruritic therapy is often directed against a variety of targets, including the epidermal barrier, immune system, or the nervous system. Topical therapy is the mainstay of dermatologic management of acute or localized itch or in patients with contraindications to systemic therapies. This review will summarize current topical therapies to treat pruritus and discuss potential future therapies. PMID:21767774

  8. Topical ketoprofen patch.

    PubMed

    Mazières, Bernard

    2005-01-01

    Although oral nonsteroidal anti-inflammatory drugs (NSAIDs) are effective in the treatment of a variety of acute and chronic pain conditions, their use may be associated with serious systemic adverse effects, particularly gastrointestinal disorders. In order to minimise the incidence of systemic events related to such agents, topical NSAIDs have been developed. Topical NSAIDs, applied as gels, creams or sprays, penetrate the skin, subcutaneous fatty tissue and muscle in amounts that are sufficient to exert a therapeutic effect on peripheral and central mechanisms in the absence of high plasma concentrations. Data indicate that topical NSAIDs are effective at relieving pain in a number of acute and chronic pain indications. This review article discusses the pharmacokinetics, efficacy and tolerability of a new formulation of ketoprofen available as a topical patch. The topical patch containing ketoprofen 100mg as the active principle has been developed using a novel delivery system that dispenses therapeutic doses of the drug directly to the site of injury. Pharmacokinetic data indicate that although plasma levels of ketoprofen are higher when the drug is administered as a patch versus a gel, the total systemic bioavailability of ketoprofen 100 mg administered via a patch is no more than 10% of that reported for ketoprofen 100 mg administered orally. Because the patch facilitates ketoprofen delivery over a 24-hour period, the drug remains continually present in the tissue subjacent to the site of application. High tissue but low plasma ketoprofen concentrations mean that while tissue concentrations are high enough to exert a therapeutic effect, plasma concentrations remain low enough to not result in systemic adverse events caused by elevated serum NSAID levels. Phase III clinical trials in patients with non-articular rheumatism and traumatic painful soft tissue injuries showed that the topical ketoprofen patch was significantly more effective than placebo at

  9. The Mathematics of Networks Science: Scale-Free, Power-Law Graphs and Continuum Theoretical Analysis

    ERIC Educational Resources Information Center

    Padula, Janice

    2012-01-01

    When hoping to initiate or sustain students' interest in mathematics teachers should always consider relevance, relevance to students' lives and in the middle and later years of instruction in high school and university, accessibility. A topic such as the mathematics behind networks science, more specifically scale-free graphs, is up-to-date,…

  10. Networking and Special Educational Institutions for the Purpose of Socialization of Children with Disabilities

    ERIC Educational Resources Information Center

    Valiullina, Gulnara V.; Fedotova, Anastasia E.

    2016-01-01

    The relevance to the article topic due to the fact that the network character of interaction of educational institutions aims at the implementation of accessible education of children with disabilities as a strategic objective of educational policy of Russian Federation. The purpose of the article is to analyze the existing models of network…

  11. Housing: Topic Paper F.

    ERIC Educational Resources Information Center

    National Council on the Handicapped, Washington, DC.

    This paper, one of a series of topic papers assessing federal laws and programs affecting persons with disabilities, addresses the issue of housing. Major federal responsibilities are to develop additional housing opportunities for persons with disabilities and to assure that currently available housing is equally open to individuals with…

  12. Topical Research: Africa.

    ERIC Educational Resources Information Center

    Lynn, Karen

    This lesson plan can be used in social studies, language arts, or library research. The instructional objective is for students to select a topic of study relating to Africa, write a thesis statement, collect information from media sources, and develop a conclusion. The teacher may assign the lesson for written or oral evaluation. The teacher…

  13. Topics for Mathematics Clubs.

    ERIC Educational Resources Information Center

    Dalton, LeRoy C., Ed.; Snyder, Henry D., Ed.

    The ten chapters in this booklet cover topics not ordinarily discussed in the classroom: Fibonacci sequences, projective geometry, groups, infinity and transfinite numbers, Pascal's Triangle, topology, experiments with natural numbers, non-Euclidean geometries, Boolean algebras, and the imaginary and the infinite in geometry. Each chapter is…

  14. Differential Topic Models.

    PubMed

    Chen, Changyou; Buntine, Wray; Ding, Nan; Xie, Lexing; Du, Lan

    2015-02-01

    In applications we may want to compare different document collections: they could have shared content but also different and unique aspects in particular collections. This task has been called comparative text mining or cross-collection modeling. We present a differential topic model for this application that models both topic differences and similarities. For this we use hierarchical Bayesian nonparametric models. Moreover, we found it was important to properly model power-law phenomena in topic-word distributions and thus we used the full Pitman-Yor process rather than just a Dirichlet process. Furthermore, we propose the transformed Pitman-Yor process (TPYP) to incorporate prior knowledge such as vocabulary variations in different collections into the model. To deal with the non-conjugate issue between model prior and likelihood in the TPYP, we thus propose an efficient sampling algorithm using a data augmentation technique based on the multinomial theorem. Experimental results show the model discovers interesting aspects of different collections. We also show the proposed MCMC based algorithm achieves a dramatically reduced test perplexity compared to some existing topic models. Finally, we show our model outperforms the state-of-the-art for document classification/ideology prediction on a number of text collections. PMID:26353238

  15. [Misoprostol: pathways, mediation and social networks for access to abortion using medication in the context of illegality in the State of Sao Paulo].

    PubMed

    Arilha, Margareth Martha

    2012-07-01

    The scope of this article is to discuss the commercialization and use of misoprostol for abortion purposes in the illegal contexts that still persist in Brazil. The information presented was collected through case studies conducted with two young women who aborted using medication - one successfully and one unsuccessfully - and two adult women who have close ties with women who used misoprostol. The study confirms the hypothesis that the diffusion and expansion of the use of misoprostol outside the hospital context is associated with the decision of women who seek lower costs, lower risks to their health and privacy. It also permits examination of the interpretation that this increase in consumption is linked to the inclusion of the medication in a set of goods that are illegally traded in Brazil, in different ways and in different contexts. As a result, women are exposed to different degrees of vulnerability depending directly on the steps taken, types of mediation used and social networks they belong to. These are the ways in which women and men obtain access to the use of misoprostol for abortion, the outcome of which may be successful or not. PMID:22872340

  16. Accessibility Videos.

    PubMed

    Kurppa, Ari; Nordlund, Marika

    2016-01-01

    It can be difficult to understand accessibility, if you do not have the personal experience. The Accessibility Centre ESKE produced short videos which demonstrate the meaning of accessibility in different situations. Videos will raise accessibility awareness of architects, other planners and professionals in the construction field and maintenance. PMID:27534282

  17. 10 CFR 2.1007 - Access.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Licenses for the Receipt of High-Level Radioactive Waste at a Geologic Repository § 2.1007 Access. (a)(1) A system to provide electronic access to the Licensing Support Network shall be provided at the... provide electronic access to the Licensing Support Network shall be provided at the NRC Web site,...

  18. 10 CFR 2.1007 - Access.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Licenses for the Receipt of High-Level Radioactive Waste at a Geologic Repository § 2.1007 Access. (a)(1) A system to provide electronic access to the Licensing Support Network shall be provided at the... provide electronic access to the Licensing Support Network shall be provided at the NRC Web site,...

  19. Challenges in Database Design with Microsoft Access

    ERIC Educational Resources Information Center

    Letkowski, Jerzy

    2014-01-01

    Design, development and explorations of databases are popular topics covered in introductory courses taught at business schools. Microsoft Access is the most popular software used in those courses. Despite quite high complexity of Access, it is considered to be one of the most friendly database programs for beginners. A typical Access textbook…

  20. Subject Access Points in Electronic Retrieval.

    ERIC Educational Resources Information Center

    Hjorland, Birger; Nielsen, Lykke Kyllesbech

    2001-01-01

    Discussion of subject access points in databases concentrates on the broader theoretical perspective. Topics include technology-driven stages in the development of subject access points; a taxonomy of subject access points; document titles; abstracts; references and citations; full text; and descriptors, identifiers, classification codes, and…

  1. Issues in Public Access: The Solomons Conferences.

    ERIC Educational Resources Information Center

    Sprehe, J. Timothy

    1993-01-01

    Reports on conferences held by federal agencies in 1991 and 1992 that addressed issues of public access to electronic government information. Topics discussed include agency information dissemination programs; public access to federal computers; security controls; and user charges. A working draft policy framework on public access to government…

  2. Network- and network-element-level parameters for configuration, fault, and performance management of optical networks

    NASA Astrophysics Data System (ADS)

    Drion, Christophe; Berthelon, Luc; Chambon, Olivier; Eilenberger, Gert; Peden, Francoise R.; Jourdan, Amaury

    1998-10-01

    With the high interest of network operators and manufacturers for wavelength division multiplexing (WDM) networking technology, the need for management systems adapted to this new technology keeps increasing. We investigated this topic and produced outputs through the specification of the functional architecture, network layered model, and through the development of new, TMN- based, information models for the management of optical networks and network elements. Based on these first outputs, defects in each layer together with parameters for performance management/monitoring have been identified for each type of optical network element, and each atomic function describing the element, including functions for both the transport of payload signals and of overhead information. The list of probable causes has been established for the identified defects. A second aspect consists in the definition of network-level parameters, if such photonic technology-related parameters are to be considered at this level. It is our conviction that some parameters can be taken into account at the network level for performance management, based on physical measurements within the network. Some parameters could possibly be used as criteria for configuration management, in the route calculation processes, including protection. The outputs of these specification activities are taken into account in the development of a manageable WDM network prototype which will be used as a test platform to demonstrate configuration, fault, protection and performance management in a real network, in the scope of the ACTS-MEPHISTO project. This network prototype will also be used in a larger size experiment in the context of the ACTS-PELICAN field trial (Pan-European Lightwave Core and Access Network).

  3. Topical diphenhydramine toxicity.

    PubMed

    Bernhardt, D T

    1991-08-01

    This paper will review an acute onset of mental confusion associated with hallucinations secondary to vigorous administration of topical Caladryl lotion and Benadryl spray in an 8-year-old boy with chickenpox. The article discusses the toxicity of both oral and topical diphenhydramine use, along with the differentiation of varicella encephalitis from diphenhydramine toxicity. Delirium can be described as an acute clouding of consciousness associated with visual and tactile hallucinations, disorientation, and misperceptions. In a child who is already suffering from an infectious illness, encephalitis must be high on the list of the physician's differential diagnosis. The physician, however, must never overlook ingestions, even from topical, over-the-counter medications. The case described illustrates this point. Although this appears to be the fourth case report on this subject, the diagnosis was partially obscured by the fact that the local pharmacist could not find any documented cases despite a computer search of diphenhydramine toxicity at the time of admission and the report of only one or two cases by the Parke-Davis pharmacist.

  4. An online system for metabolic network analysis

    PubMed Central

    Cicek, Abdullah Ercument; Qi, Xinjian; Cakmak, Ali; Johnson, Stephen R.; Han, Xu; Alshalwi, Sami; Ozsoyoglu, Zehra Meral; Ozsoyoglu, Gultekin

    2014-01-01

    Metabolic networks have become one of the centers of attention in life sciences research with the advancements in the metabolomics field. A vast array of studies analyzes metabolites and their interrelations to seek explanations for various biological questions, and numerous genome-scale metabolic networks have been assembled to serve for this purpose. The increasing focus on this topic comes with the need for software systems that store, query, browse, analyze and visualize metabolic networks. PathCase Metabolomics Analysis Workbench (PathCaseMAW) is built, released and runs on a manually created generic mammalian metabolic network. The PathCaseMAW system provides a database-enabled framework and Web-based computational tools for browsing, querying, analyzing and visualizing stored metabolic networks. PathCaseMAW editor, with its user-friendly interface, can be used to create a new metabolic network and/or update an existing metabolic network. The network can also be created from an existing genome-scale reconstructed network using the PathCaseMAW SBML parser. The metabolic network can be accessed through a Web interface or an iPad application. For metabolomics analysis, steady-state metabolic network dynamics analysis (SMDA) algorithm is implemented and integrated with the system. SMDA tool is accessible through both the Web-based interface and the iPad application for metabolomics analysis based on a metabolic profile. PathCaseMAW is a comprehensive system with various data input and data access subsystems. It is easy to work with by design, and is a promising tool for metabolomics research and for educational purposes. Database URL: http://nashua.case.edu/PathwaysMAW/Web PMID:25267793

  5. Topical Drug Delivery for Chronic Rhinosinusitis

    PubMed Central

    Liang, Jonathan; Lane, Andrew P.

    2013-01-01

    Chronic rhinosinusitis is a multifactorial disorder that may be heterogeneous in presentation and clinical course. While the introduction of endoscopic sinus surgery revolutionized surgical management and has led to significantly improved patient outcomes, medical therapy remains the foundation of long-term care of chronic rhinosinusitis, particularly in surgically recalcitrant cases. A variety of devices and pharmaceutical agents have been developed to apply topical medical therapy to the sinuses, taking advantage of the access provided by endoscopic surgery. The goal of topical therapy is to address the inflammation, infection, and mucociliary dysfunction that underlies the disease. Major factors that impact success include the patient’s sinus anatomy and the dynamics of the delivery device. Despite a growing number of topical treatment options, the evidence-based literature to support their use is limited. In this article, we comprehensively review current delivery methods and the available topical agents. We also discuss biotechnological advances that promise enhanced delivery in the future, and evolving pharmacotherapeutical compounds that may be added to rhinologist’s armamentarium. A complete understand of topical drug delivery is increasingly essential to the management of chronic rhinosinusitis when traditional forms of medical therapy and surgery have failed. PMID:23525506

  6. Classification of Distributed Data Using Topic Modeling and Maximum Variation Sampling

    SciTech Connect

    Patton, Robert M; Beaver, Justin M; Potok, Thomas E

    2011-01-01

    From a management perspective, understanding the information that exists on a network and how it is distributed provides a critical advantage. This work explores the use of topic modeling as an approach to automatically determine the classes of information that exist on an organization's network, and then use the resultant topics as centroid vectors for the classification of individual documents in order to understand the distribution of information topics across the enterprise network. The approach is tested using the 20 Newsgroups dataset.

  7. Privacy-Preserving Discovery of Topic-Based Events from Social Sensor Signals: An Experimental Study on Twitter

    PubMed Central

    Nguyen, Duc T.; Jung, Jai E.

    2014-01-01

    Social network services (e.g., Twitter and Facebook) can be regarded as social sensors which can capture a number of events in the society. Particularly, in terms of time and space, various smart devices have improved the accessibility to the social network services. In this paper, we present a social software platform to detect a number of meaningful events from information diffusion patterns on such social network services. The most important feature is to process the social sensor signal for understanding social events and to support users to share relevant information along the social links. The platform has been applied to fetch and cluster tweets from Twitter into relevant categories to reveal hot topics. PMID:24955388

  8. Viral vaccines: selected topics.

    PubMed

    Kańtoch, M

    1996-01-01

    Significant role of viruses in pathology, their dominating position in etiology of infectious diseases point at the special position of active prophylactic procedures based on vaccination. The real role and value of viral vaccines of classic and modern generations, the limitation of immune potency in suppression of defence mechanisms, some problems of immunization against virus vertical transmission are presented in the paper. The reader may find tables which cumulate selected but significant patterns of viral vaccines and vaccinations, and selected papers devoted to topics discussed. PMID:9017153

  9. Topical urea in dermatology.

    PubMed

    Banerjee, P K; Choudhury, A K; Panja, S K

    1990-03-01

    For years research has been conducted to find a cutaneous moisturizer that is effective, easily available and relatively inexpensive urea, as a atopical agent, is all of this and is also a mild keratolytic. A trial was conducted over 200 patients suffering from a variety of disorders that were selected and using urea topically as urea 10 (10%), urea-20 lotion (20%), Urea-HC (with hydrocartisanl). The agent was applied twice daily for a maximum period of 8 weeks. Results indicate that urea is an effective moisturizer and in promotes the penetration of hydrocelisone into the skin.

  10. Topically induced diphenhydramine toxicity.

    PubMed

    Reilly, J F; Weisse, M E

    1990-01-01

    We report the case of a 2 1/2-year-old child who manifested acute anticholinergic toxicity after the applications of a topical calamine-antihistamine lotion. This mechanism of diphenhydramine toxicity is uncommon, with only a few other case reports noted in the literature. This case is also intriguing in that this child had an underlying varicella illness with fever that tended to obscure the picture. This report describes the characteristic history and physical examination pertinent to anticholinergic toxicity, varicella complication considerations, and case management.

  11. Novel topical therapeutics.

    PubMed

    Bleier, Benjamin S

    2010-06-01

    Intranasal drug delivery is a rapidly growing field that offers the potential for enhanced treatment of local and systemic disease. Novel preclinical screening tools such as in vitro assays and 3-dimensional imaging are currently being used to improve drug design and delivery. In addition, new evidence has emerged underlining the importance of surgical marsupialization of the sinuses to allow for improved topical delivery. Although multiple barriers to administration and absorption exist, implantable therapeutics using new classes of drug-eluting polymers allow for prolonged, site-specific drug delivery and hold great promise in overcoming these obstacles.

  12. Recent topics in Japan.

    PubMed

    Inaba, Y

    1996-08-01

    In Japan, the concern about ethical issues in preventive medicine, especially in epidemiological investigation, has been gradually increasing in recent years. In this paper I introduce the following four topics: 1. privacy protection and the computer, 2. informed consent and publication, 3. the attitudes toward ethics among epidemiologists, 4. the attitudes toward epidemiological investigation among examinees. In my opinion, Japanese epidemiologists should give more attention to general ethical principles (Respect for persons, Beneficence) and to the practical methods to apply them in their research works.

  13. Partners: Promoting Accessible Recreation.

    ERIC Educational Resources Information Center

    Sable, Janet; Gravink, Jill

    1995-01-01

    The Promoting Accessible Recreation through Networking, Education, Resources and Services (PARTNERS) Project, a partnership between Northeast Passage, the University of New Hampshire, and Granite State Independent Living Foundation, helps create barrier-free recreation for individuals with physical disabilities. The paper describes PARTNERS and…

  14. Internet 2 Access Grid.

    ERIC Educational Resources Information Center

    Simco, Greg

    2002-01-01

    Discussion of the Internet 2 Initiative, which is based on collaboration among universities, businesses, and government, focuses on the Access Grid, a Computational Grid that includes interactive multimedia within high-speed networks to provide resources to enable remote collaboration among the research community. (Author/LRW)

  15. Implications of the Dynamics of the New Networked Economy for E-Business Start-Ups: The Case of Philips' Access Point.

    ERIC Educational Resources Information Center

    Tovstiga, George; Fantner, Ernest J.

    2000-01-01

    Examines implications of the networked economy for e-commerce business start-ups. Revisits the notion of "value" and "value creation" in a network context. Examines "value" relative to technological innovation. Looks at implications of the network environment for the organization and transformation of the enterprise's internal governance called…

  16. Topical Therapy Primer for Nondermatologists.

    PubMed

    Jewell, Jolene R; Myers, Sarah A

    2015-11-01

    A representative assortment of topical therapies is discussed here with the goal of emphasizing the most commonly encountered diagnoses and treatments for nondermatologists. When using topical therapies, carefully consider the proper active ingredient, potency, vehicle, and quantity of medication. If topical therapy is ineffective, question whether the medication is being used properly, whether the diagnosis is correct, and whether the topical may be contributing to the problem. Examples of the topical contributing to the problem include tinea incognito exacerbated by topical steroid use and allergic contact dermatitis to topical steroid excipients. For some patients, even maximum topical therapy is insufficient and systemic treatment is required. At this point, consultation with a dermatologist may be helpful.

  17. Sentinel Network

    Cancer.gov

    The Sentinel Network is an integrated, electronic, national medical product safety initiative that compiles information about the safe and effective use of medical products accessible to patients and healthcare practitioners.

  18. Topic-Prominence in Interlanguage.

    ERIC Educational Resources Information Center

    Fuller, Judith W.; Gundel, Jeannette K.

    1987-01-01

    Investigates the role of topic-comment structure and the frequency of topic-prominence in the oral interlanguage of Chinese- Japanese-, Korean-, Arabic-, Farsi-, and Spanish-speaking adult students of English as a second language. Results indicate that second language learning is generally characterized by an early topic-comment stage, independent…

  19. Web Accessibility and Accessibility Instruction

    ERIC Educational Resources Information Center

    Green, Ravonne A.; Huprich, Julia

    2009-01-01

    Section 508 of the Americans with Disabilities Act (ADA) mandates that programs and services be accessible to people with disabilities. While schools of library and information science (SLIS*) and university libraries should model accessible Web sites, this may not be the case. This article examines previous studies about the Web accessibility of…

  20. A systematic review of the status of children's school access in low- and middle-income countries between 1998 and 2013: using the INDEPTH Network platform to fill the research gaps

    PubMed Central

    Kamanda, Mamusu; Sankoh, Osman

    2015-01-01

    Background The framework for expanding children's school access in low- and middle-income countries (LMICs) has been directed by universal education policies as part of Education for All since 1990. In measuring progress to universal education, a narrow conceptualisation of access which dichotomises children's participation as being in or out of school has often been assumed. Yet, the actual promise of universal education goes beyond this simple definition to include retention, progression, completion, and learning. Objective Our first objective was to identify gaps in the literature on children's school access using the zones of exclusion of the Consortium for Research on Educational Access, Transition, and Equity as a framework. Second, we gave consideration to how these gaps can be met by using longitudinal and cross-country data from Health and Demographic Surveillance System (HDSS) sites within the International Network for the Demographic Evaluation of Population and Their Health (INDEPTH) in LMICs. Design Using Web of Science, we conducted a literature search of studies published in international peer-reviewed journals between 1998 and 2013 in LMICs. The phrases we searched included six school outcomes: school enrolment, school attendance, grade progression, school dropout, primary to secondary school transition, and school completion. From our search, we recorded studies according to: 1) school outcomes; 2) whether longitudinal data were used; and 3) whether data from more than one country were analysed. Results The area of school access most published is enrolment followed by attendance and dropout. Primary to secondary school transition and grade progression had the least number of publications. Of 132 publications which we found to be relevant to school access, 33 made use of longitudinal data and 17 performed cross-country analyses. Conclusions The majority of studies published in international peer-reviewed journals on children's school access between

  1. Third Annual Foreign Acquisitions Workshop: Improving Access to Foreign Gray Literature

    NASA Technical Reports Server (NTRS)

    1993-01-01

    The theme of the Third Annual Foreign Acquisitions Workshop was the acquisition of and access to foreign (non-U.S.) gray literature. Individual presentations addressed general topics related to the value and scope of gray literature, specialized and foreign gray-literature sources, intellectual property issues, and U.S. Federal Agency activities. Additional topics focused on electronic access and evaluation techniques and the current and potential uses of networking technology. The workshop papers are presented in their entirety or in abstract or outline form. Appendices include a listing of databases that include foreign gray literature, a bibliography, and a report on U.S.-Japan cooperation in the use of scientific and technical information.

  2. Networked Resources: Usenet.

    ERIC Educational Resources Information Center

    Nickerson, Gord

    1992-01-01

    Describes the development of Usenet, the User's Network, a computer network that distributes group discussions (newsgroups) on different topics. Network News software is described, the rapid growth in popularity and heavy network traffic is discussed, and a hierarchical classification scheme to limit the amount of information for users is…

  3. Public understanding of geoscientific topics

    NASA Astrophysics Data System (ADS)

    Münch, Ute; Lauterjung, Jörn

    2014-05-01

    Geoscientific topics and their consequences for the society are becoming more and more important for our daily life. Natural hazards such as flood and storm or the consequences of the climate change are urgent tasks and great challenges we have to tackle. Cascading natural hazards or environmental risks, can't be evaluated as single events by one scientific discipline, they rather need the expertise of different experts. The same applies for slowly progressive processes such as the climate change and its different aftereffects. More than ever politicians, decision makers, but also the public are asking for comprehensive background information and data to discuss activity options and to develop sustainable solutions. The improvement of public knowledge about science, their assets and drawbacks, chances and risks is getting crucial. To paint a comprehensive picture of different factors, correlations and dependencies the pooling of expertise is required. Thus eight research centres of the research field "Earth and Environment" of the Helmholtz-Association, Germany's largest scientific research organisation are currently building up a knowledge platform. Scientists of different disciplines will provide background information and explain their latest findings in an understandable way. Infographics, maps and animations will be applied to simplify and interpret complicated facts and findings. In addition to the web presence target group-specific products and activities will be organized. To meet the expectations of the different stakeholders an intensive dialog is aspired: round table discussions, exhibitions in museums and public places, tweeds are envisaged. In the beginning the partners will concentrate on the topics "consequences of the climate change", "pollutant dispersion" and "natural hazards/meteorological extreme events". The project is called Earth System Knowledge Platform (ESKP) coordinated by the German Research Centre for Geosciences (GFZ) and the Helmholtz

  4. Macroscopic characterisations of Web accessibility

    NASA Astrophysics Data System (ADS)

    Lopes, Rui; Carriço, Luis

    2010-12-01

    The Web Science framework poses fundamental questions on the analysis of the Web, by focusing on how microscopic properties (e.g. at the level of a Web page or Web site) emerge into macroscopic properties and phenomena. One research topic on the analysis of the Web is Web accessibility evaluation, which centres on understanding how accessible a Web page is for people with disabilities. However, when framing Web accessibility evaluation on Web Science, we have found that existing research stays at the microscopic level. This article presents an experimental study on framing Web accessibility evaluation into Web Science's goals. This study resulted in novel accessibility properties of the Web not found at microscopic levels, as well as of Web accessibility evaluation processes themselves. We observed at large scale some of the empirical knowledge on how accessibility is perceived by designers and developers, such as the disparity of interpretations of accessibility evaluation tools warnings. We also found a direct relation between accessibility quality and Web page complexity. We provide a set of guidelines for designing Web pages, education on Web accessibility, as well as on the computational limits of large-scale Web accessibility evaluations.

  5. Hubless satellite communications networks

    NASA Technical Reports Server (NTRS)

    Robinson, Peter Alan

    1994-01-01

    Frequency Comb Multiple Access (FCMA) is a new combined modulation and multiple access method which will allow cheap hubless Very Small Aperture Terminal (VSAT) networks to be constructed. Theoretical results show bandwidth efficiency and power efficiency improvements over other modulation and multiple access methods. Costs of the VSAT network are reduced dramatically since a hub station is not required.

  6. Topics in statistical mechanics

    SciTech Connect

    Elser, V.

    1984-05-01

    This thesis deals with four independent topics in statistical mechanics: (1) the dimer problem is solved exactly for a hexagonal lattice with general boundary using a known generating function from the theory of partitions. It is shown that the leading term in the entropy depends on the shape of the boundary; (2) continuum models of percolation and self-avoiding walks are introduced with the property that their series expansions are sums over linear graphs with intrinsic combinatorial weights and explicit dimension dependence; (3) a constrained SOS model is used to describe the edge of a simple cubic crystal. Low and high temperature results are derived as well as the detailed behavior near the crystal facet; (4) the microscopic model of the lambda-transition involving atomic permutation cycles is reexamined. In particular, a new derivation of the two-component field theory model of the critical behavior is presented. Results for a lattice model originally proposed by Kikuchi are extended with a high temperature series expansion and Monte Carlo simulation. 30 references.

  7. Characterizing interdisciplinarity of researchers and research topics using web search engines.

    PubMed

    Sayama, Hiroki; Akaishi, Jin

    2012-01-01

    Researchers' networks have been subject to active modeling and analysis. Earlier literature mostly focused on citation or co-authorship networks reconstructed from annotated scientific publication databases, which have several limitations. Recently, general-purpose web search engines have also been utilized to collect information about social networks. Here we reconstructed, using web search engines, a network representing the relatedness of researchers to their peers as well as to various research topics. Relatedness between researchers and research topics was characterized by visibility boost-increase of a researcher's visibility by focusing on a particular topic. It was observed that researchers who had high visibility boosts by the same research topic tended to be close to each other in their network. We calculated correlations between visibility boosts by research topics and researchers' interdisciplinarity at the individual level (diversity of topics related to the researcher) and at the social level (his/her centrality in the researchers' network). We found that visibility boosts by certain research topics were positively correlated with researchers' individual-level interdisciplinarity despite their negative correlations with the general popularity of researchers. It was also found that visibility boosts by network-related topics had positive correlations with researchers' social-level interdisciplinarity. Research topics' correlations with researchers' individual- and social-level interdisciplinarities were found to be nearly independent from each other. These findings suggest that the notion of "interdisciplinarity" of a researcher should be understood as a multi-dimensional concept that should be evaluated using multiple assessment means.

  8. Diabetes network.

    PubMed

    2016-07-01

    Diabetes UK has launched a network of information and support for commissioning and improvement in diabetes care. The network is free to join and offers monthly updates on good practice from around the UK, a forum for sharing ideas and learning, and access to Diabetes UK resources. PMID:27369708

  9. Innovation Networks

    NASA Astrophysics Data System (ADS)

    Pyka, Andreas; Scharnhorst, Andrea

    The idea for this book started when we organized a topical workshop entitled "Innovation Networks - New Approaches in Modeling and Analyzing" (held in Augsburg, Germany in October 2005), under the auspices of Exystence, a network of excellence funded in the European Union's Fifth Framework Program. Unlike other conferences on innovation and networks, however, this workshop brought together scientists from economics, sociology, communication science, science and technology studies, and physics. With this book we aim to build further on a bridge connecting the bodies of knowledge on networks in economics, the social sciences and, more recently, statistical physics.

  10. Discovering Health Topics in Social Media Using Topic Models

    PubMed Central

    Paul, Michael J.; Dredze, Mark

    2014-01-01

    By aggregating self-reported health statuses across millions of users, we seek to characterize the variety of health information discussed in Twitter. We describe a topic modeling framework for discovering health topics in Twitter, a social media website. This is an exploratory approach with the goal of understanding what health topics are commonly discussed in social media. This paper describes in detail a statistical topic model created for this purpose, the Ailment Topic Aspect Model (ATAM), as well as our system for filtering general Twitter data based on health keywords and supervised classification. We show how ATAM and other topic models can automatically infer health topics in 144 million Twitter messages from 2011 to 2013. ATAM discovered 13 coherent clusters of Twitter messages, some of which correlate with seasonal influenza (r = 0.689) and allergies (r = 0.810) temporal surveillance data, as well as exercise (r = .534) and obesity (r = −.631) related geographic survey data in the United States. These results demonstrate that it is possible to automatically discover topics that attain statistically significant correlations with ground truth data, despite using minimal human supervision and no historical data to train the model, in contrast to prior work. Additionally, these results demonstrate that a single general-purpose model can identify many different health topics in social media. PMID:25084530

  11. Efinaconazole topical solution, 10%: formulation development program of a new topical treatment of toenail onychomycosis.

    PubMed

    Bhatt, V; Pillai, R

    2015-07-01

    Transungual drug delivery of antifungals is considered highly desirable to treat common nail disorders such as onychomycosis, due to localized effects, and improved adherence resulting from minimal systemic adverse events. However, the development of effective topical therapies has been hampered by poor nail penetration. An effective topical antifungal must permeate through, and under the dense keratinized nail plate to the site of infection in the nail bed and nail matrix. We present here the formulation development program to provide effective transungual and subungual delivery of efinaconazole, the first topical broad spectrum triazole specifically developed for onychomycosis treatment. We discuss the important aspects encompassing the formulation development program for efinaconazole topical solution, 10%, focusing on its solubility in a number of solvents, in vitro penetration through the nail, and in vivo efficacy. Efinaconazole topical solution, 10% is a stable, non-lacquer, antifungal with a unique combination of ingredients added to an alcohol-based formulation to provide low surface tension and good wetting properties. This low surface tension is believed to affect effective transungual delivery of efinaconazole and believed to provide a dual mode of delivery by accessing the nail bed by wicking into the space between the nail and nail plate. PMID:25940933

  12. Efinaconazole topical solution, 10%: formulation development program of a new topical treatment of toenail onychomycosis.

    PubMed

    Bhatt, V; Pillai, R

    2015-07-01

    Transungual drug delivery of antifungals is considered highly desirable to treat common nail disorders such as onychomycosis, due to localized effects, and improved adherence resulting from minimal systemic adverse events. However, the development of effective topical therapies has been hampered by poor nail penetration. An effective topical antifungal must permeate through, and under the dense keratinized nail plate to the site of infection in the nail bed and nail matrix. We present here the formulation development program to provide effective transungual and subungual delivery of efinaconazole, the first topical broad spectrum triazole specifically developed for onychomycosis treatment. We discuss the important aspects encompassing the formulation development program for efinaconazole topical solution, 10%, focusing on its solubility in a number of solvents, in vitro penetration through the nail, and in vivo efficacy. Efinaconazole topical solution, 10% is a stable, non-lacquer, antifungal with a unique combination of ingredients added to an alcohol-based formulation to provide low surface tension and good wetting properties. This low surface tension is believed to affect effective transungual delivery of efinaconazole and believed to provide a dual mode of delivery by accessing the nail bed by wicking into the space between the nail and nail plate.

  13. Computer Networks and Networking: A Primer.

    ERIC Educational Resources Information Center

    Collins, Mauri P.

    1993-01-01

    Provides a basic introduction to computer networks and networking terminology. Topics addressed include modems; the Internet; TCP/IP (Transmission Control Protocol/Internet Protocol); transmission lines; Internet Protocol numbers; network traffic; Fidonet; file transfer protocol (FTP); TELNET; electronic mail; discussion groups; LISTSERV; USENET;…

  14. Using Social Network Graphs as Visualization Tools to Influence Peer Selection Decision-Making Strategies to Access Information about Complex Socioscientific Issues

    ERIC Educational Resources Information Center

    Yoon, Susan A.

    2011-01-01

    This study extends previous research that explores how visualization affordances that computational tools provide and social network analyses that account for individual- and group-level dynamic processes can work in conjunction to improve learning outcomes. The study's main hypothesis is that when social network graphs are used in instruction,…

  15. Access Denied

    ERIC Educational Resources Information Center

    Villano, Matt

    2008-01-01

    Building access control (BAC)--a catchall phrase to describe the systems that control access to facilities across campus--has traditionally been handled with remarkably low-tech solutions: (1) manual locks; (2) electronic locks; and (3) ID cards with magnetic strips. Recent improvements have included smart cards and keyless solutions that make use…

  16. Open Access

    ERIC Educational Resources Information Center

    Suber, Peter

    2012-01-01

    The Internet lets us share perfect copies of our work with a worldwide audience at virtually no cost. We take advantage of this revolutionary opportunity when we make our work "open access": digital, online, free of charge, and free of most copyright and licensing restrictions. Open access is made possible by the Internet and copyright-holder…

  17. Topical fat reduction.

    PubMed

    Greenway, F L; Bray, G A; Heber, D

    1995-11-01

    The fat on women's thighs is more difficult to mobilize due to increased alpha-2 adrenergic receptor activity induced by estrogen. Lipolysis can be initiated through adipocyte receptor stimulation (beta adrenergic) or inhibition (adenosine or alpha-2 adrenergic) or by inhibition of phosphodiesterase. Since many women desire regional thigh fat loss, a series of clinical trials were initiated using one thigh as a double-blinded control. Trial #1: Five overweight women had injections of isoproterenol at intervals around the thigh three times a week for 4 weeks with diet and walking. Trial #2: Five overweight woman had ointment containing forskolin, yohimbine and aminophylline applied to the thigh five times a week for 4 weeks after hypertonic warm soaks with a diet and walking. Trial #3: Eighteen overweight women were divided into three groups of six and trial #2 was repeated with each agent alone vs. placebo using forskolin, yohimbine or aminophylline in separate ointments. Trial #4: Thirty overweight women had 10% aminophylline ointment applied to the thigh five times a week for 6 weeks with diet and walking. Chemistry panel, theophylline level and patch testing were performed. Trial #5: Twelve women had trial #4 repeated with 2% aminophylline cream without a diet or walking. Trial #6: Trial #5 was repeated with 0.5% aminophylline cream. All trials except yohimbine ointment gave significantly more girth loss from the treated thigh (p < 0.05 to p < 0.001). Chemistry panel showed no toxicity. Theophylline was undetectable and patch testing was negative. We conclude that topical fat reduction for women's thighs can be achieved without diet or exercise. PMID:8697059

  18. Advances Made in the Next Generation of Satellite Networks

    NASA Technical Reports Server (NTRS)

    Bhasin, Kul B.

    1999-01-01

    Because of the unique networking characteristics of communications satellites, global satellite networks are moving to the forefront in enhancing national and global information infrastructures. Simultaneously, broadband data services, which are emerging as the major market driver for future satellite and terrestrial networks, are being widely acknowledged as the foundation for an efficient global information infrastructure. In the past 2 years, various task forces and working groups around the globe have identified pivotal topics and key issues to address if we are to realize such networks in a timely fashion. In response, industry, government, and academia undertook efforts to address these topics and issues. A workshop was organized to provide a forum to assess the current state-of-the-art, identify key issues, and highlight the emerging trends in the next-generation architectures, data protocol development, communication interoperability, and applications. The Satellite Networks: Architectures, Applications, and Technologies Workshop was hosted by the Space Communication Program at the NASA Lewis Research Center in Cleveland, Ohio. Nearly 300 executives and technical experts from academia, industry, and government, representing the United States and eight other countries, attended the event (June 2 to 4, 1998). The program included seven panels and invited sessions and nine breakout sessions in which 42 speakers presented on technical topics. The proceedings covers a wide range of topics: access technology and protocols, architectures and network simulations, asynchronous transfer mode (ATM) over satellite networks, Internet over satellite networks, interoperability experiments and applications, multicasting, NASA interoperability experiment programs, NASA mission applications, and Transmission Control Protocol/Internet Protocol (TCP/IP) over satellite: issues, relevance, and experience.

  19. Hot Topic Talk 2

    NASA Astrophysics Data System (ADS)

    Schmidt, Piet O.

    2016-05-01

    Precision spectroscopy is a driving force for the development of our physical understanding. However, only few atomic and molecular systems of interest have been accessible for precision spectroscopy in the past, since they miss a suitable transition for laser cooling and internal state detection. This restriction can be overcome in trapped ions through quantum logic spectroscopy. Coherent laser manipulation originally developed in the context of quantum information processing with trapped ions allow the combination of the special spectroscopic properties of one ion species (spectroscopy ion) with the excellent control over another species (logic or cooling ion). I will show how the internal state of a molecular ion can be detected non-destructively on a co-trapped cooling ion by implementing a quantum logic algorithm involving only coherent laser manipulation on the molecular ion. An optical dipole force tuned to near one of the molecule's resonances interacts with the molecular ion only if it is in a specific state. The resulting change in the motional state of a two-ion crystal formed by the molecular and atomic ion can be efficiently detected through the latter. More specifically, we detect if the MgH+ molecule is in the rotational state J = 1 in the vibrational and electronic ground state. We observe quantum jumps into and out of this state that are driven by ambient black-body radiation. We use the detuning dependence of the dipole force to perform spectroscopy on an electronic transition. This represents a first step towards extending the exquisite control achieved over selected atomic species to much more complex molecular ions.

  20. Steps toward Creating Fully Accessible Reading Assessments

    ERIC Educational Resources Information Center

    Thurlow, Martha L.

    2010-01-01

    The National Accessible Reading Assessment Projects (NARAP) have been conducting research and engaging in other activities to pull together a full view of the issues and potential solutions for developing reading assessments that are fully accessible and produce valid results for students with disabilities. To introduce this topic, the assumptions…

  1. Ready Reference Tools: EBSCO Topic Search and SIRS Researcher.

    ERIC Educational Resources Information Center

    Goins, Sharon; Dayment, Lu

    1998-01-01

    Discussion of ready reference and current events collections in high school libraries focuses on a comparison of two CD-ROM services, EBSCO Topic Search and the SIRS Researcher. Considers licensing; access; search strategies; viewing articles; currency; printing; added value features; and advantages of CD-ROMs. (LRW)

  2. TM4L: Creating and Browsing Educational Topic Maps

    ERIC Educational Resources Information Center

    Dicheva, Darina; Dichev, Christo

    2006-01-01

    In this article, we describe TM4L, an environment for building, maintaining and using standards-based, ontology-aware e-learning repositories. It is based on the idea that concept-driven access to learning material implemented as a topic map can bridge the gap between a learner and targeted knowledge. One of the driving goals of this work is to…

  3. Resources for Topics in Art.

    ERIC Educational Resources Information Center

    Van Noate, Judith, Comp.

    This guide for conducting library research on topics in art or the work of a particular artist presents suggestions for utilizing four categories of resources: books, dictionaries and encyclopedias, indexes, and a periodicals and serials list (PASL). Three topics are researched as examples: the contemporary artist and author Frank Stella, the…

  4. Working Topics for Students' Papers.

    ERIC Educational Resources Information Center

    Marting, Janet

    Students enrolled in composition classes may provide the answer to the dilemma of coming up with a writing topic: work--the "four letter word." Most, if not all, students have already become part of the labor force. The theme of "work" is naturally successful because it centers around a topic students know well, something that is within their…

  5. Discourse Structure, Topicality, and Questioning.

    ERIC Educational Resources Information Center

    Van Kuppevelt, Jan

    1995-01-01

    This paper presents an alternative approach to discourse structure according to which topicality is the general organizing principle in discourse. This approach accounts for the fact that the segmentation structure of discourse is in correspondence with the hierarchy of topics defined for the discourse units. (52 references) (JL)

  6. Linguistic Extensions of Topic Models

    ERIC Educational Resources Information Center

    Boyd-Graber, Jordan

    2010-01-01

    Topic models like latent Dirichlet allocation (LDA) provide a framework for analyzing large datasets where observations are collected into groups. Although topic modeling has been fruitfully applied to problems social science, biology, and computer vision, it has been most widely used to model datasets where documents are modeled as exchangeable…

  7. Gaining Access.

    ERIC Educational Resources Information Center

    Kennedy, Mike

    2000-01-01

    Discusses issues schools and universities have encountered in complying with the Americans with Disabilities Act (ADA) and making their facilities more accessible to the disabled. The ADA's vagueness and the architect's need for understanding the regulations is highlighted. (GR)

  8. Equal Access.

    ERIC Educational Resources Information Center

    De Patta, Joe

    2003-01-01

    Presents an interview with Stephen McCarthy, co-partner and president of Equal Access ADA Consulting Architects of San Diego, California, about designing schools to naturally integrate compliance with the Americans with Disabilities Act (ADA). (EV)

  9. Capital access.

    PubMed

    Towne, Jennifer

    2004-06-01

    To maintain their viability, hospitals are being compelled to invest in big capital projects such as information technology and renovation and construction. This gatefold examines the trends in credit and capital, and how they affect hospitals' access to money.

  10. Providing Internet Access for North Carolina's Libraries.

    ERIC Educational Resources Information Center

    Burgin, Robert

    1996-01-01

    Because North Carolina's telecommunications services have been unable to provide cost-effective, statewide dial-access service to public libraries, the state library has had to identify a suitable alternative for public library network access. This article outlines the state library's efforts to provide access to the Internet and to electronic…

  11. Revocable Anonymous Access to the Internet?

    ERIC Educational Resources Information Center

    Claessens, Joris; Diaz, Claudia; Goemans, Caroline; Preneel, Bart; Vandewalle, Joos; Dumortier, Jos

    2003-01-01

    Users of telecommunications networks are concerned about privacy, and desire anonymous access, while some organizations are concerned about how this anonymous access might be abused. Proposes a solution for revocable anonymous access to the Internet. Presents some legal background and motivation for such a solution. Indicates some difficulties and…

  12. Electronic Neural Networks

    NASA Technical Reports Server (NTRS)

    Thakoor, Anil

    1990-01-01

    Viewgraphs on electronic neural networks for space station are presented. Topics covered include: electronic neural networks; electronic implementations; VLSI/thin film hybrid hardware for neurocomputing; computations with analog parallel processing; features of neuroprocessors; applications of neuroprocessors; neural network hardware for terrain trafficability determination; a dedicated processor for path planning; neural network system interface; neural network for robotic control; error backpropagation algorithm for learning; resource allocation matrix; global optimization neuroprocessor; and electrically programmable read only thin-film synaptic array.

  13. Irregular access to the power distribution network in Brazil's residential sector: a delinquent payment problem, or the quest for a right beyond the law?

    SciTech Connect

    da Silva, Neilton Fidelis; Rosa, Luiz Pinguelli

    2008-08-15

    Clandestine residential consumers should not be rubber-stamped as criminals. Siphoning off electricity does not constitute an illegal action, but is rather the only alternative open to marginalized layers of society who rate electricity in their homes as a right to which they should have access. (author)

  14. Mental mechanisms for topics identification.

    PubMed

    Massey, Louis

    2014-01-01

    Topics identification (TI) is the process that consists in determining the main themes present in natural language documents. The current TI modeling paradigm aims at acquiring semantic information from statistic properties of large text datasets. We investigate the mental mechanisms responsible for the identification of topics in a single document given existing knowledge. Our main hypothesis is that topics are the result of accumulated neural activation of loosely organized information stored in long-term memory (LTM). We experimentally tested our hypothesis with a computational model that simulates LTM activation. The model assumes activation decay as an unavoidable phenomenon originating from the bioelectric nature of neural systems. Since decay should negatively affect the quality of topics, the model predicts the presence of short-term memory (STM) to keep the focus of attention on a few words, with the expected outcome of restoring quality to a baseline level. Our experiments measured topics quality of over 300 documents with various decay rates and STM capacity. Our results showed that accumulated activation of loosely organized information was an effective mental computational commodity to identify topics. It was furthermore confirmed that rapid decay is detrimental to topics quality but that limited capacity STM restores quality to a baseline level, even exceeding it slightly. PMID:24744775

  15. Mental mechanisms for topics identification.

    PubMed

    Massey, Louis

    2014-01-01

    Topics identification (TI) is the process that consists in determining the main themes present in natural language documents. The current TI modeling paradigm aims at acquiring semantic information from statistic properties of large text datasets. We investigate the mental mechanisms responsible for the identification of topics in a single document given existing knowledge. Our main hypothesis is that topics are the result of accumulated neural activation of loosely organized information stored in long-term memory (LTM). We experimentally tested our hypothesis with a computational model that simulates LTM activation. The model assumes activation decay as an unavoidable phenomenon originating from the bioelectric nature of neural systems. Since decay should negatively affect the quality of topics, the model predicts the presence of short-term memory (STM) to keep the focus of attention on a few words, with the expected outcome of restoring quality to a baseline level. Our experiments measured topics quality of over 300 documents with various decay rates and STM capacity. Our results showed that accumulated activation of loosely organized information was an effective mental computational commodity to identify topics. It was furthermore confirmed that rapid decay is detrimental to topics quality but that limited capacity STM restores quality to a baseline level, even exceeding it slightly.

  16. Topic Model for Graph Mining.

    PubMed

    Xuan, Junyu; Lu, Jie; Zhang, Guangquan; Luo, Xiangfeng

    2015-12-01

    Graph mining has been a popular research area because of its numerous application scenarios. Many unstructured and structured data can be represented as graphs, such as, documents, chemical molecular structures, and images. However, an issue in relation to current research on graphs is that they cannot adequately discover the topics hidden in graph-structured data which can be beneficial for both the unsupervised learning and supervised learning of the graphs. Although topic models have proved to be very successful in discovering latent topics, the standard topic models cannot be directly applied to graph-structured data due to the "bag-of-word" assumption. In this paper, an innovative graph topic model (GTM) is proposed to address this issue, which uses Bernoulli distributions to model the edges between nodes in a graph. It can, therefore, make the edges in a graph contribute to latent topic discovery and further improve the accuracy of the supervised and unsupervised learning of graphs. The experimental results on two different types of graph datasets show that the proposed GTM outperforms the latent Dirichlet allocation on classification by using the unveiled topics of these two models to represent graphs.

  17. The future of topical analgesics.

    PubMed

    Arnstein, Paul M

    2013-07-01

    Topically applied analgesic therapies have been used throughout history to treat a variety of patient conditions that present with pain. Before modem pharmaceuticals became readily available, mud-based emollients, salves, cold therapies, and other natural remedies were often used. Now we have effective therapies and are developing advanced topical analgesics as we learn more about the physiology and pathophysiology of pain. The use of topical analgesics may be associated with fewer patient systemic side effects than are seen with oral, parenteral, or transdermally administered agents, making the topical route of administration attractive to prescribers and patients. With further refinement of existing drugs and the development of novel agents, topical analgesics may offer relief for treating patient pain conditions that are currently challenging to treat, such as pain resulting from burns, wound debridement, and pressure ulcers. Recognizing the value of a multimodal approach, topical analgesics may offer a therapeutic option that can become part of a comprehensive treatment plan for the patient. With continued advancements in targeted drug-delivery systems, topical analgesics may be able to provide a method to prevent or reverse the phenomena of peripheral and central sensitization, or the neuroplastic changes believed to be responsible for the transition from acute to chronic pain states in patients. For those patients at risk for developing chronic pain states, such as complex regional pain syndrome, the combination of cutaneous stimulation (achieved through rubbing during application) and analgesic effects produced by the drug itself may prevent the disabling pain that often emerges during the subacute phase of disease. In summary, better utilization of currently available topical analgesics and continued research promise to ensure that topical analgesics are, and will continue to be, important tools in the treatment of patients with resistant pain. PMID

  18. Topical Steroid-Damaged Skin

    PubMed Central

    Abraham, Anil; Roga, Gillian

    2014-01-01

    Topical steroids, commonly used for a wide range of skin disorders, are associated with side effects both systemic and cutaneous. This article aims at bringing awareness among practitioners, about the cutaneous side effects of easily available, over the counter, topical steroids. This makes it important for us as dermatologists to weigh the usefulness of topical steroids versus their side effects, and to make an informed decision regarding their use in each individual based on other factors such as age, site involved and type of skin disorder. PMID:25284849

  19. Parallel architectures and neural networks

    SciTech Connect

    Calianiello, E.R. )

    1989-01-01

    This book covers parallel computer architectures and neural networks. Topics include: neural modeling, use of ADA to simulate neural networks, VLSI technology, implementation of Boltzmann machines, and analysis of neural nets.

  20. Hemodialysis access - self care

    MedlinePlus

    Kidney failure - chronic-hemodialysis access; Renal failure - chronic-hemodialysis access; Chronic renal insufficiency - hemodialysis access; Chronic kidney failure - hemodialysis access; Chronic renal failure - hemodialysis access; dialysis - hemodialysis access

  1. Conversational topics in transsexual persons.

    PubMed

    Van Borsel, John; Cayzeele, Miet; Heirman, Eva; T'sjoen, Guy

    2014-06-01

    Abstract In general, speech language therapy for transsexual persons focuses on pitch and pitch variation and more recently also on resonance. Other communicative aspects are dealt with far less often, especially language. This study investigated to what extent conversational topics might need attention in therapy for transsexual persons. A total of 111 males, 116 females, 28 male-to-female and 18 female-to-male transsexuals were asked to indicate on a list with 34 topics how often they speak about each topic (never, sometimes, often) in conversations with males, with females and in a gender mixed group. Results showed that transsexual persons behave in accordance with the desired gender. However, they also tend to adopt a position depending on the gender of their conversational partner. It can be concluded that in general it is not necessary to pay attention to conversational topics in therapy for transsexual persons.

  2. Erythromycin and Benzoyl Peroxide Topical

    MedlinePlus

    ... doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking. Be sure to mention other topical medications for acne. Your doctor may need to ...

  3. Universities as Hubs for Next-Generation Networks: A Model for Universities to Spur 21st Century Internet Access and Innovation in Their Communities

    ERIC Educational Resources Information Center

    Lennett, Benjamin; Morris, Sarah J.; Byrum, Greta

    2012-01-01

    Based on a request for information (RFI) submitted to The University Community Next Generation Innovation Project (Gig.U), the paper describes a model for universities to develop next generation broadband infrastructure in their communities. In the our view universities can play a critical role in spurring next generation networks into their…

  4. Easy Access

    ERIC Educational Resources Information Center

    Gettelman, Alan

    2009-01-01

    School and university restrooms, locker and shower rooms have specific ADA accessibility requirements that serve the needs of staff, students and campus visitors who are disabled as a result of injury, illness or age. Taking good care of them is good for the reputation of a sensitive community institution, and fosters positive public relations.…

  5. Access Denied

    ERIC Educational Resources Information Center

    Raths, David

    2012-01-01

    As faculty members add online and multimedia elements to their courses, colleges and universities across the country are realizing that there is a lot of work to be done to ensure that disabled students (and employees) have equal access to course material and university websites. Unfortunately, far too few schools consider the task a top priority.…

  6. Expanding Access

    ERIC Educational Resources Information Center

    Roach, Ronald

    2007-01-01

    There is no question that the United States lags behind most industrialized nations in consumer access to broadband Internet service. For many policy makers and activists, this shortfall marks the latest phase in the struggle to overcome the digital divide. To remedy this lack of broadband affordability and availability, one start-up firm--with…

  7. Collections and Services for the Spanish-Speaking: Accessibility.

    ERIC Educational Resources Information Center

    Marquis, Solina Kasten

    2003-01-01

    Discusses making public library collections accessible to Spanish-speaking users and describes the consequences that can result from inattention to linguistic and cultural accessibility. Topics include cataloging issues and solutions; labeling; shelving; signage; electronic access; Spanish language training for staff; intercultural communication;…

  8. Detecting Hotspot Information Using Multi-Attribute Based Topic Model.

    PubMed

    Wang, Jing; Li, Li; Tan, Feng; Zhu, Ying; Feng, Weisi

    2015-01-01

    Microblogging as a kind of social network has become more and more important in our daily lives. Enormous amounts of information are produced and shared on a daily basis. Detecting hot topics in the mountains of information can help people get to the essential information more quickly. However, due to short and sparse features, a large number of meaningless tweets and other characteristics of microblogs, traditional topic detection methods are often ineffective in detecting hot topics. In this paper, we propose a new topic model named multi-attribute latent dirichlet allocation (MA-LDA), in which the time and hashtag attributes of microblogs are incorporated into LDA model. By introducing time attribute, MA-LDA model can decide whether a word should appear in hot topics or not. Meanwhile, compared with the traditional LDA model, applying hashtag attribute in MA-LDA model gives the core words an artificially high ranking in results meaning the expressiveness of outcomes can be improved. Empirical evaluations on real data sets demonstrate that our method is able to detect hot topics more accurately and efficiently compared with several baselines. Our method provides strong evidence of the importance of the temporal factor in extracting hot topics.

  9. Detecting Hotspot Information Using Multi-Attribute Based Topic Model.

    PubMed

    Wang, Jing; Li, Li; Tan, Feng; Zhu, Ying; Feng, Weisi

    2015-01-01

    Microblogging as a kind of social network has become more and more important in our daily lives. Enormous amounts of information are produced and shared on a daily basis. Detecting hot topics in the mountains of information can help people get to the essential information more quickly. However, due to short and sparse features, a large number of meaningless tweets and other characteristics of microblogs, traditional topic detection methods are often ineffective in detecting hot topics. In this paper, we propose a new topic model named multi-attribute latent dirichlet allocation (MA-LDA), in which the time and hashtag attributes of microblogs are incorporated into LDA model. By introducing time attribute, MA-LDA model can decide whether a word should appear in hot topics or not. Meanwhile, compared with the traditional LDA model, applying hashtag attribute in MA-LDA model gives the core words an artificially high ranking in results meaning the expressiveness of outcomes can be improved. Empirical evaluations on real data sets demonstrate that our method is able to detect hot topics more accurately and efficiently compared with several baselines. Our method provides strong evidence of the importance of the temporal factor in extracting hot topics. PMID:26496635

  10. Detecting Hotspot Information Using Multi-Attribute Based Topic Model

    PubMed Central

    Wang, Jing; Li, Li; Tan, Feng; Zhu, Ying; Feng, Weisi

    2015-01-01

    Microblogging as a kind of social network has become more and more important in our daily lives. Enormous amounts of information are produced and shared on a daily basis. Detecting hot topics in the mountains of information can help people get to the essential information more quickly. However, due to short and sparse features, a large number of meaningless tweets and other characteristics of microblogs, traditional topic detection methods are often ineffective in detecting hot topics. In this paper, we propose a new topic model named multi-attribute latent dirichlet allocation (MA-LDA), in which the time and hashtag attributes of microblogs are incorporated into LDA model. By introducing time attribute, MA-LDA model can decide whether a word should appear in hot topics or not. Meanwhile, compared with the traditional LDA model, applying hashtag attribute in MA-LDA model gives the core words an artificially high ranking in results meaning the expressiveness of outcomes can be improved. Empirical evaluations on real data sets demonstrate that our method is able to detect hot topics more accurately and efficiently compared with several baselines. Our method provides strong evidence of the importance of the temporal factor in extracting hot topics. PMID:26496635

  11. Data acquisition systems for the high energy and Nuclotron internal target polarimeters with network access to polarization calculation results and raw data

    NASA Astrophysics Data System (ADS)

    Isupov, A. Yu.

    2005-01-01

    Online data acquisition (DAQ) system for the Nuclotron Internal Target Polarimeter (ITP) at the LHE, JINR is explained in respects of design and implementation, based on the distributed data acquisition and processing system qdpb. Software modules specific for this implementation (dependent of ITP data contents and hardware layout) are discussed briefly in comparison with them for the High Energy Polarimeter (HEP) at the LHE, JINR. User access methods to both raw data and results of polarization calculations of the ITP and HEP are described.

  12. Developer Network

    SciTech Connect

    2012-08-21

    NREL's Developer Network, developer.nrel.gov, provides data that users can access to provide data to their own analyses, mobile and web applications. Developers can retrieve the data through a Web services API (application programming interface). The Developer Network handles overhead of serving up web services such as key management, authentication, analytics, reporting, documentation standards, and throttling in a common architecture, while allowing web services and APIs to be maintained and managed independently.

  13. Campus Networking Strategies: An Introduction.

    ERIC Educational Resources Information Center

    Roberts, Michael M.

    1988-01-01

    This article is adapted from the introduction to EDUCOM's forthcoming book, Campus Networking Strategies, which includes 10 case study chapters detailing academic experiences with computer networking. Topics discussed in the introduction include network issues for management, networking economics, engineering and telecommunications issues, and…

  14. Topics

    ERIC Educational Resources Information Center

    Mathematics Teaching, 1971

    1971-01-01

    Problems involving divisibility, the ten coin triangle, five times a week with 4 D, a nomogram for the lens formula, the box and ladder problem, chains of circles, tessellating hexagons, topological woggles, and numbers of triangles are discussed. (CT)

  15. Topics

    ERIC Educational Resources Information Center

    Mathematics Teaching, 1971

    1971-01-01

    Notes on De Morgan's rules; a perpetual calendar; the use of coloured rods; a balance problem; a graphical approach to natural logarithms; a problem in geometric probability; and the parallelogram law of forces. (MM)

  16. Networks Around the World.

    ERIC Educational Resources Information Center

    Online & CD-ROM Review, 1997

    1997-01-01

    Examines the topic of networked information. Discusses the possibility of a global stock exchange, the utility of environmental information on the Internet, the Internet in India, and Internet user types and habits according to a survey conducted in Denmark. (AEF)

  17. Haloprogin: a Topical Antifungal Agent

    PubMed Central

    Harrison, E. F.; Zwadyk, P.; Bequette, R. J.; Hamlow, E. E.; Tavormina, P. A.; Zygmunt, W. A.

    1970-01-01

    Haloprogin was shown to be a highly effective agent for the treatment of experimentally induced topical mycotic infections in guinea pigs. Its in vitro spectrum of activity also includes yeasts, yeastlike fungi (Candida species), and certain gram-positive bacteria. The in vitro and in vivo antifungal activity of haloprogin against dermatophytes was equal to that observed with tolnaftate. The striking differences between the two agents were the marked antimonilial and selective antibacterial activities shown by haloprogin, contrasted with the negligible activities found with tolnaftate. Addition of serum decreased the in vitro antifungal activity of haloprogin to a greater extent than that of tolnaftate; however, diminished antifungal activity was not observed when haloprogin was applied topically to experimental dermatophytic infections. Based on its broad spectrum of antimicrobial activity, haloprogin may prove to be a superior topical agent in the treatment of dermatophytic and monilial infections in man. PMID:5422306

  18. Cognitive Wireless Communications - A paradigm shift in dealing with radio resources as a prerequisite for the wireless network of the future - An overview on the topic of cognitive wireless technologies

    NASA Astrophysics Data System (ADS)

    Haustein, Thomas; Stanczak, Slawomir; Wolisz, Adam; Jondral, Friedrich; Schotten, Hans; Kraemer, Rolf; Mück, Markus; Mennenga, Horst; Bender, Paul

    2016-07-01

    Wireless radio communications systems form the basis for mobile network connections in the digital society. A limited amount of radio spectrum and a spatially densified use of wireless communications systems require a resource-efficient use of the spectrum. Mechanisms of cognitive radio may hold the key to a more efficient use of the available spectrum under consideration of quality of service requirements. These mechanisms take advantage of location-specific knowledge of the wireless channel occupation in the dimensions of frequency, time, location and direction in space and therefore enable co-existent and reliable wireless communication. The authors give an introduction to the status of cognitive wireless communication technology, which represents the starting point of a series of research projects promoted by BMBF during 2012-2014.

  19. Topical therapies in hyperhidrosis care.

    PubMed

    Pariser, David M; Ballard, Angela

    2014-10-01

    Primary focal hyperhidrosis affects 3% of the US population; about the same number as psoriasis. More than half of these patients have primary focal axillary hyperhidrosis: sweating that is beyond what is anticipated or necessary for thermoregulation. Most topical therapies are based on aluminum salts, which work by a chemical reaction that forms plugs in the eccrine sweat ducts. Topical anticholinergics may also be used. Instruction on proper methods and timing of antiperspirants enhances effect and may be effective alone or in combination with other treatments in patients with hyperhidrosis.

  20. Topical therapies in hyperhidrosis care.

    PubMed

    Pariser, David M; Ballard, Angela

    2014-10-01

    Primary focal hyperhidrosis affects 3% of the US population; about the same number as psoriasis. More than half of these patients have primary focal axillary hyperhidrosis: sweating that is beyond what is anticipated or necessary for thermoregulation. Most topical therapies are based on aluminum salts, which work by a chemical reaction that forms plugs in the eccrine sweat ducts. Topical anticholinergics may also be used. Instruction on proper methods and timing of antiperspirants enhances effect and may be effective alone or in combination with other treatments in patients with hyperhidrosis. PMID:25152341

  1. Topical treatments for hypertrophic scars.

    PubMed

    Zurada, Joanna M; Kriegel, David; Davis, Ira C

    2006-12-01

    Hypertrophic scars represent an abnormal, exaggerated healing response after skin injury. In addition to cosmetic concern, scars may cause pain, pruritus, contractures, and other functional impairments. Therapeutic modalities include topical medications, intralesional corticosteroids, laser therapy, and cryosurgery. Topical therapies, in particular, have become increasingly popular because of their ease of use, comfort, noninvasiveness, and relatively low cost. This review will discuss the properties and effectiveness of these agents, including pressure therapy, silicone gel sheeting and ointment, polyurethane dressing, onion extract, imiquimod 5% cream, and vitamins A and E in the prevention and treatment of hypertrophic scars. PMID:17097399

  2. Hemodialysis access procedures

    MedlinePlus

    Kidney failure - chronic-dialysis access; Renal failure - chronic-dialysis access; Chronic renal insufficiency-dialysis access; Chronic kidney failure-dialysis access; Chronic renal failure-dialysis access

  3. Disruption of the H-bond network in the main access channel of catalase-peroxidase modulates enthalpy and entropy of Fe(III) reduction.

    PubMed

    Vlasits, Jutta; Bellei, Marzia; Jakopitsch, Christa; De Rienzo, Francesca; Furtmüller, Paul G; Zamocky, Marcel; Sola, Marco; Battistuzzi, Gianantonio; Obinger, Christian

    2010-06-01

    Catalase-peroxidases are the only heme peroxidases with substantial hydrogen peroxide dismutation activity. In order to understand the role of the redox chemistry in their bifunctional activity, catalatically-active and inactive mutant proteins have been probed in spectroelectrochemical experiments. In detail, wild-type KatG from Synechocystis has been compared with variants with (i) disrupted KatG-typical adduct (Trp122-Tyr249-Met275), (ii) mutation of the catalytic distal His123-Arg119 pair, and (iii) altered accessibility to the heme cavity (Asp152, Ser335) and modified charge at the substrate channel entrance (Glu253). A valuable insight into the mechanism of reduction potential (E degrees ') modulation in KatG has been obtained from the parameterization of the corresponding enthalpic and entropic components, determined from the analysis of the temperature dependence of E degrees '. Moreover, model structures of ferric and ferrous Synechocystis KatG have been computed and used as reference to analyze and discuss the experimental data. The results, discussed by reference to published resonance Raman data on the strength of the proximal iron-imidazole bond and catalytic properties, demonstrate that E degrees ' of the Fe(III)/Fe(II) couple is not strongly correlated with the bifunctional activity. Besides the importance of an intact Trp-Tyr-Met adduct, it is the architecture of the long and constricted main channel that distinguishes KatGs from monofunctional peroxidases. An ordered matrix of oriented water dipoles is important for H(2)O(2) oxidation. Its disruption results in modification of enthalpic and entropic contributions to E degrees ' that reflect reduction-induced changes in polarity, electrostatics, continuity and accessibility of solvent to the metal center as well as alterations in solvent reorganization.

  4. The impact of a novel franchise clinic network on access to medicines and vaccinations in Kenya: a cross-sectional study

    PubMed Central

    Adhvaryu, Achyuta

    2012-01-01

    Objectives To study the impact of a new franchise health clinic model (The HealthStore Foundation's CFWShops) on access to vaccinations and treatment for acute illnesses in a nationally representative sample of children in Kenya. Design The authors used multivariate linear and count regressions to examine associations between receipt of vaccinations or treatment and proximity to a franchise health clinic, adjusting for individual, household and clinic attributes as well as region fixed effects. Setting Demographic and Health Survey data from Kenya, 2008–2009. Participants 6079 Kenyan children younger than 5 years, of whom 2310 reported recent acute illness. Main outcome measures Outcomes for all children were number of polio doses received, number of DPT doses received, receipt of BCG vaccine, receipt of measles vaccine and number of total vaccinations received. Outcomes for acutely ill children were receipt of any medical treatment, treatment for fever, treatment for malaria and treatments specifically stocked by CFWShops. Results Children living within 30 km of a CFWShop received 0.129 (p=0.017) and 0.113 (p=0.025) more DPT and polio doses, respectively; and 0.285 more total vaccinations (p=0.023). Among acutely ill children, CFWShop proximity was associated with significant increases in the probabilities of receiving any medical treatment (0.142; p<0.001), treatment for fever (0.117; p=0.007) and treatments specifically stocked by CFWShops (0.064; p=0.015). Use of CFWShop services was not significantly different for lower-income vis-a-vis higher-income households. Conclusions The franchise health clinic model could substantially increase access to essential vaccinations and treatments in low-income countries. Moreover, the model's benefits may accrue to lesser- and higher-income households alike. PMID:22786948

  5. Trends in biomedical informatics: most cited topics from recent years

    PubMed Central

    Kim, Hyeon-Eui; Jiang, Xiaoqian; Kim, Jihoon

    2011-01-01

    Biomedical informatics is a young, highly interdisciplinary field that is evolving quickly. It is important to know which published topics in generalist biomedical informatics journals elicit the most interest from the scientific community, and whether this interest changes over time, so that journals can better serve their readers. It is also important to understand whether free access to biomedical informatics articles impacts their citation rates in a significant way, so authors can make informed decisions about unlock fees, and journal owners and publishers understand the implications of open access. The topics and JAMIA articles from years 2009 and 2010 that have been most cited according to the Web of Science are described. To better understand the effects of free access in article dissemination, the number of citations per month after publication for articles published in 2009 versus 2010 was compared, since there was a significant change in free access to JAMIA articles between those years. Results suggest that there is a positive association between free access and citation rate for JAMIA articles. PMID:22180873

  6. Trends in biomedical informatics: most cited topics from recent years.

    PubMed

    Kim, Hyeon-Eui; Jiang, Xiaoqian; Kim, Jihoon; Ohno-Machado, Lucila

    2011-12-01

    Biomedical informatics is a young, highly interdisciplinary field that is evolving quickly. It is important to know which published topics in generalist biomedical informatics journals elicit the most interest from the scientific community, and whether this interest changes over time, so that journals can better serve their readers. It is also important to understand whether free access to biomedical informatics articles impacts their citation rates in a significant way, so authors can make informed decisions about unlock fees, and journal owners and publishers understand the implications of open access. The topics and JAMIA articles from years 2009 and 2010 that have been most cited according to the Web of Science are described. To better understand the effects of free access in article dissemination, the number of citations per month after publication for articles published in 2009 versus 2010 was compared, since there was a significant change in free access to JAMIA articles between those years. Results suggest that there is a positive association between free access and citation rate for JAMIA articles. PMID:22180873

  7. Topical Knowledge and ESL Writing

    ERIC Educational Resources Information Center

    He, Ling; Shi, Ling

    2012-01-01

    This study investigates the effects of topical knowledge on ESL (English as a Second Language) writing performance in the English Language Proficiency Index (LPI), a standardized English proficiency test used by many post-secondary institutions in western Canada. The participants were 50 students with different levels of English proficiency…

  8. Conducting Surveys on Sensitive Topics

    ERIC Educational Resources Information Center

    Pryor, John H.

    2004-01-01

    Many institutions are surveying students about sensitive topics such as alcohol and drug use, sexual behavior, and academic dishonesty. Yet these can be some of the most difficult surveys to administer successfully, given reluctance on the part of respondents both to participate and to provide truthful answers. (Contains 1 table.)

  9. Topical pharmacology of imidazole antifungals.

    PubMed

    Holt, R J

    1976-01-01

    Four imidazole derivatives have now undergone extensive open and comparative trials as topical agents in dermatomycoses and vaginal candidosis. They are chlormidazole (Chemie Grünenthal), clotrimazole (Bayer), miconazole (Janssen) and econazole (Janssen, Cilag-Chemie); all also have some antibacterial activity. Many other imidazoles have been marketed, usually as antiprotozoal or anthelminthic agents, and some of these have some antimycotic activity as well as other miscellaneous therapeutic properties. The mode of action of imidazole antimycotic agents is discussed; after prolonged topical application to animals and human subjects, systemic absorption is negligible. All four agents which are available as cream, powder, lotion or vaginal tablets have many sucessful studies to their credit, often with clinical and mycological cure rates of over 80% in a variety of dermatomycoses and in vaginal candidosis. The relative value of these topical agents is discussed, and it is suggested that in severe and extensive dermatomycoses consideration should be given to the systemic use of miconazole in support of topical therapy.

  10. Topic Development in USENET Newsgroups.

    ERIC Educational Resources Information Center

    Osborne, Larry N.

    1998-01-01

    USENET newsgroup topics are created, and they evolve, mutate, and become extinct in ways fundamentally different from spoken dialog. These differences can be explained partially by the asynchronous nature of electronic communication, as well as by other factors unique to such wide-scale multi-user media. (Author)

  11. Topics in Biomedical Optics: Introduction

    NASA Astrophysics Data System (ADS)

    Hebden, Jeremy C.; Boas, David A.; George, John S.; Durkin, Anthony J.

    2003-06-01

    The field of biomedical optics is experiencing tremendous growth. Biomedical technologies contribute in the creation of devices used in healthcare of various specialties (ophthalmology, cardiology, anesthesiology, and immunology, etc.). Recent research in biomedical optics is discussed. Overviews of meetings held at the 2002 Optical Society of America Biomedical Topical Meetings are presented.

  12. Vocational Education Today: Topical Issues.

    ERIC Educational Resources Information Center

    Kenway, Jane, Ed.; Tregenza, Karen, Ed.; Watkins, Peter, Ed.

    This book contains 13 papers examining topical issues in vocational education and training (VET) in Victoria, Australia. The following papers are included: "Vocational Education and Schooling: The Changing Scene" (Jane Kenway, Sue Willis, Peter Watkins, Karen Tregenza); "The Enterprise Approach" (James Mulraney); "VET Programs at James Harrison…

  13. Seven topics in perturbative QCD

    SciTech Connect

    Buras, A.J.

    1980-09-01

    The following topics of perturbative QCD are discussed: (1) deep inelastic scattering; (2) higher order corrections to e/sup +/e/sup -/ annihilation, to photon structure functions and to quarkonia decays; (3) higher order corrections to fragmentation functions and to various semi-inclusive processes; (4) higher twist contributions; (5) exclusive processes; (6) transverse momentum effects; (7) jet and photon physics.

  14. The Health Curriculum: 500 Topics.

    ERIC Educational Resources Information Center

    Byrd, Oliver E.

    2001-01-01

    This 1958 paper divides 500 health topics into 20 categories: health as a social accomplishment/social problem; nutrition; physical fitness; mental health and disease; heredity/eugenics; infection/immunity; chronic and degenerative disease; substance abuse; skin care; vision, hearing, and speech; dental health; safety; physical environment; health…

  15. Topics in optics and music

    NASA Astrophysics Data System (ADS)

    Sparks, Andrew W.

    2012-10-01

    While the use of optics in the playback of music has been a tremendously successful technology and laser light shows are a common occurrence, other intersections of optics and music tend to be less well known. Topics such as optics-based instruments, performance tools and effects, instrument characterization and manufacturing, recording, playback, and signal processing are explored.

  16. The pharmacology of topical analgesics.

    PubMed

    Barkin, Robert L

    2013-07-01

    Pain management of patients continues to pose challenges to clinicians. Given the multiple dimensions of pain--whether acute or chronic, mild, moderate, or severe, nociceptive or neuropathic--a multimodal approach may be needed. Fortunately, clinicians have an array of nonpharmacologic and pharmacologic treatment choices; however, each modality must be chosen carefully, because some often used oral agents are associated with safety and tolerability issues that restrict their use in certain patients. In particular, orally administered nonsteroidal antiinflammatory drugs, opioids, antidepressants, and anticonvulsants are known to cause systemic adverse effects in some patients. To address this problem, a number of topical therapies in various therapeutic classes have been developed to reduce systemic exposure and minimize the risks of patients developing adverse events. For example, topical nonsteroidal anti-inflammatory drug formulations produce a site-specific effect (ie, cyclo-oxygenase inhibition) while decreasing the systemic exposure that may lead to undesired effects in patients. Similarly, derivatives of acetylsalicylic acid (ie, salicylates) are used in topical analgesic formulations that do not significantly enter the patient's systemic circulation. Salicylates, along with capsaicin, menthol, and camphor, compose the counterirritant class of topical analgesics, which produce analgesia by activating and then desensitizing epidermal nociceptors. Additionally, patches and creams that contain the local anesthetic lidocaine, alone or co-formulated with other local anesthetics, are also used to manage patients with select acute and chronic pain states. Perhaps the most common topical analgesic modality is the cautious application of cutaneous cold and heat. Such treatments may decrease pain not by reaching the target tissue through systemic distribution, but by acting more directly on the affected tissue. Despite the tolerability benefits associated with avoiding

  17. Application of Nail Polish During Topical Management of Onychomycosis

    PubMed Central

    Del Rosso, James Q.

    2016-01-01

    Topical antifungal management of toenail onychomycosis has been fraught with several therapeutic challenges including difficulty gaining access to the site of infection and the need for prolonged durations of therapy. In addition, there has been a marked lack of information on the impact of toenail polish application on drug penetration after application. This article reviews available data from studies evaluating the effect of nail polish on antifungal drag penetration using ex vivo laboratory models with cadaver fingernail plates with both tavaborole 5% solution and efinaconazole 10% solution. In addition, changes in nail polish appearance and color transfer to applicators are also discussed, with changes noted with topical efinaconazole. Importantly, there are no data on whether or not nail polish application alters the efficacy of these topical agents.

  18. Application of Nail Polish During Topical Management of Onychomycosis

    PubMed Central

    Del Rosso, James Q.

    2016-01-01

    Topical antifungal management of toenail onychomycosis has been fraught with several therapeutic challenges including difficulty gaining access to the site of infection and the need for prolonged durations of therapy. In addition, there has been a marked lack of information on the impact of toenail polish application on drug penetration after application. This article reviews available data from studies evaluating the effect of nail polish on antifungal drag penetration using ex vivo laboratory models with cadaver fingernail plates with both tavaborole 5% solution and efinaconazole 10% solution. In addition, changes in nail polish appearance and color transfer to applicators are also discussed, with changes noted with topical efinaconazole. Importantly, there are no data on whether or not nail polish application alters the efficacy of these topical agents. PMID:27672416

  19. An Easily Accessible Self-Healing Transparent Film Based on a 2D Supramolecular Network of Hydrogen-Bonding Interactions between Polymeric Chains.

    PubMed

    Roy, Nabarun; Tomović, Željko; Buhler, Eric; Lehn, Jean-Marie

    2016-09-12

    Self-healing polymers hold great promise for the future, enhancing in particular the longevity of polymeric materials. We describe a self-healing covalent polymer, presenting an extensive array of hydrogen-bonding sites based on the combination of urea, urethane, and bis-acyl-hydrazine units. Solvent-cast thin-films prepared by polycondensation of a commercially available dihydrazide and a diisocyanate prepolymer exhibited excellent room temperature autonomous healing with almost full recovery of mechanical properties when two parts of a cut film were overlapped and gently pressed together. This autonomous healing upon damage may be attributed to the supramolecular dynamics of multiple lateral inter-chain hydrogen-bonding interactions between the polymer chains. The solid-state structure of a model compound incorporating the same structural backbone corroborates the existence of an extensive two-dimensional supramolecular hydrogen-bonding network. PMID:27226034

  20. [The concepts of health access].

    PubMed

    Sanchez, Raquel Maia; Ciconelli, Rozana Mesquita

    2012-03-01

    This article describes four dimensions of health access-availability, acceptability, ability to pay and information-correlating these dimensions to indicators and discussing the complexity of the concept of access. For a study of these four dimensions, searches were conducted using the PubMed/MEDLINE, LILACS, SciELO, and World Health Organization Library & Information Networks for Knowledge (WHOLIS) databases. Large-circulation media vehicles, such as The Economist, The Washington Post, and the BBC network were also searched. The concept of health access has become more complex with time. The first analyses, carried out in the 1970s, suggested a strong emphasis on geographical (availability) and financial (ability to pay) aspects. More recently, the literature has focused on less tangible aspects, such as cultural, educational, and socioeconomic issues, incorporating the element of acceptability into the notion of health access. The literature also shows that information provides the starting point for access to health, in association with health empowerment and literacy for health care decision-making. The study concludes that improvements in access to health and the guarantee of equity will not be achieved by initiatives focusing on health care systems alone, but rather will depend on intersectoral actions and social and economic policies aimed at eliminating income and education differences.